Journal articles: 'Whole Cell Voltage Clamp'

1

Jackson, Meyer B. "Whole-Cell Voltage Clamp Recording." Current Protocols in Neuroscience 00, no. 1 (September 1997): 6.6.1–6.6.30. http://dx.doi.org/10.1002/0471142301.ns0606s00.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Grygorczyk, Ryszard, and Michael A. Bridges. "Whole-cell chloride conductances in cultured brushed human nasal epithelial cells." Canadian Journal of Physiology and Pharmacology 70, no. 8 (August 1, 1992): 1134–41. http://dx.doi.org/10.1139/y92-157.

Full text

Abstract:

Human airway epithelial cells were obtained by nasal brushing, thus avoiding the use of proteolytic enzymes for cell isolation. Whole-cell Cl− conductances were studied in these cells by means of the patch-clamp technique. During whole-cell recordings, cell swelling activated a Cl− conductance that was blocked by indanyloxyacetic acid (48 ± 10% inhibition at 50 μM). The swelling-induced current outwardly rectified and showed inactivation at depolarizing voltages (≥ +60 mV) and activation at hyperpolarizing voltages (≤ −30 mV). The voltage sensitivity of current activation was approximately twice that of inactivation. Another Cl− current with different kinetics was observed when nonswollen airway cells were stimulated with ionomycin (2 μM) in the presence of 1 mM Ca2+. The Ca2+-induced current exhibited activation during depolarizing voltage steps (≥ +40 mV) and inactivation during hyperpolarizing voltage steps (≤ −40 mV). In contrast to the swelling-induced current, the activation of Ca2+-induced current was less sensitive to voltage compared with its inactivation. Tail current analysis suggested that Cl− channels having a linear current–voltage relation mediate the response to Ca2+. This study indicates that brushed human nasal epithelial cells possess Cl− conductances that are regulated by cell swelling and Ca2+ and that they represent a useful in vitro model for studying ion transport in epithelia.Key words: chloride channels, epithelia, airway, patch clamp.

APA, Harvard, Vancouver, ISO, and other styles

3

Harrison, Reid R., Ilya Kolb, Suhasa B. Kodandaramaiah, Alexander A. Chubykin, Aimei Yang, Mark F. Bear, Edward S. Boyden, and Craig R. Forest. "Microchip amplifier for in vitro, in vivo, and automated whole cell patch-clamp recording." Journal of Neurophysiology 113, no. 4 (February 15, 2015): 1275–82. http://dx.doi.org/10.1152/jn.00629.2014.

Full text

Abstract:

Patch clamping is a gold-standard electrophysiology technique that has the temporal resolution and signal-to-noise ratio capable of reporting single ion channel currents, as well as electrical activity of excitable single cells. Despite its usefulness and decades of development, the amplifiers required for patch clamping are expensive and bulky. This has limited the scalability and throughput of patch clamping for single-ion channel and single-cell analyses. In this work, we have developed a custom patch-clamp amplifier microchip that can be fabricated using standard commercial silicon processes capable of performing both voltage- and current-clamp measurements. A key innovation is the use of nonlinear feedback elements in the voltage-clamp amplifier circuit to convert measured currents into logarithmically encoded voltages, thereby eliminating the need for large high-valued resistors, a factor that has limited previous attempts at integration. Benchtop characterization of the chip shows low levels of current noise [1.1 pA root mean square (rms) over 5 kHz] during voltage-clamp measurements and low levels of voltage noise (8.2 μV rms over 10 kHz) during current-clamp measurements. We demonstrate the ability of the chip to perform both current- and voltage-clamp measurement in vitro in HEK293FT cells and cultured neurons. We also demonstrate its ability to perform in vivo recordings as part of a robotic patch-clamping system. The performance of the patch-clamp amplifier microchip compares favorably with much larger commercial instrumentation, enabling benchtop commoditization, miniaturization, and scalable patch-clamp instrumentation.

APA, Harvard, Vancouver, ISO, and other styles

4

Shkodrov, Georgi B. "Computer program for performing whole-cell voltage-clamp experiments." Computer Methods and Programs in Biomedicine 48, no. 3 (December 1995): 241–46. http://dx.doi.org/10.1016/0169-2607(95)01696-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Wolfe, Joshua T., Bryan A. Krantz, G. Jonah A. Rainey, John A. T. Young, and R. John Collier. "Whole-cell Voltage Clamp Measurements of Anthrax Toxin Pore Current." Journal of Biological Chemistry 280, no. 47 (September 23, 2005): 39417–22. http://dx.doi.org/10.1074/jbc.m509049200.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Nasi, E. "Whole-cell clamp of dissociated photoreceptors from the eye of Lima scabra." Journal of General Physiology 97, no. 1 (January 1, 1991): 35–54. http://dx.doi.org/10.1085/jgp.97.1.35.

Full text

Abstract:

Voltage-dependent membrane currents were investigated in enzymatically dissociated photoreceptors of Lima scabra using the whole-cell clamp technique. Depolarizing steps to voltages more positive than -10 mV elicit a transient inward current followed by a delayed, sustained outward current. The outward current is insensitive to replacement of a large fraction of extracellular Cl- with the impermeant anion glucuronate. Superfusion with tetraethylammonium and 4-aminopyridine reversibly abolishes the outward current, and internal perfusion with cesium also suppresses it, indicating that it is mediated by potassium channels. Isolation of the inward current reveals a fast activation kinetics, the peak amplitude occurring as early as 4-5 ms after stimulus onset, and a relatively rapid, though incomplete inactivation. Within the range of voltages examined, spanning up to +90 mV, reversal was not observed. The inward current is not sensitive to tetrodotoxin at concentrations up to 10 microM, and survives replacement of extracellular Na with tetramethylammonium. On the other hand, it is completely eliminated by calcium removal from the perfusing solution, and it is partially blocked by submillimolar concentrations of cadmium, suggesting that it is entirely due to voltage-dependent calcium channels. Analysis of the kinetics and voltage dependence of the isolated calcium current indicates the presence of two components, possibly reflecting the existence of separate populations of channels. Barium and strontium can pass through these channels, though less easily than calcium. Both the activation and the inactivation become significantly more sluggish when these ions serve as the charge carrier. A large fraction of the outward current is activated by preceding calcium influx. Suppression of this calcium-dependent potassium current shows a small residual component resembling the delayed rectifier. In addition, a transient outward current sensitive to 4-aminopyridine (Ia) could also be identified. The relevance of such conductance mechanisms in the generation of the light response in Lima photoreceptors is discussed.

APA, Harvard, Vancouver, ISO, and other styles

7

Mleux, Benoit Saint, and L. E. Moore. "Active Dendritic Membrane Properties of XenopusLarval Spinal Neurons Analyzed With a Whole Cell Soma Voltage Clamp." Journal of Neurophysiology 83, no. 3 (March 1, 2000): 1381–93. http://dx.doi.org/10.1152/jn.2000.83.3.1381.

Full text

Abstract:

Voltage- and current-clamp measurements of inwardly directed currents were made from the somatic regions of Xenopus laevisspinal neurons. Current-voltage ( I-V) curves determined under voltage clamp, but not current clamp, were able to indicate a negative slope conductance in neurons that showed strong accommodating action potential responses to a constant current stimulation. Voltage-clamp I-V curves from repetitive firing neurons did not have a net negative slope conductance and had identical I-V plots under current clamp. Frequency domain responses indicate negative slope conductances with different properties with or without tetrodotoxin, suggesting that both sodium and calcium currents are present in these spinal neurons. The currents obtained from a voltage clamp of the somatic region were analyzed in terms of spatially controlled soma membrane currents and additional currents from dendritic potential responses. Linearized frequency domain analysis in combination with both voltage- and current-clamp responses over a range of membrane potentials was essential for an accurate determination of consistent neuronal model behavior. In essence, the data obtained at resting or hyperpolarized membrane potentials in the frequency domain were used to determine the electrotonic structure, while both the frequency and time domain data at depolarized potentials were required to characterize the voltage-dependent channels. Finally, the dendritic and somatic membrane properties were used to reconstruct the action potential behavior and quantitatively predict the dependence of neuronal firing properties on electrotonic structure. The reconstructed action potentials reproduced the behavior of two broad distributions of interneurons characterized by their degree of accommodation. These studies suggest that in addition to the ionic conductances, electrotonic structure is correlated with the action potential behavior of larval neurons.

APA, Harvard, Vancouver, ISO, and other styles

8

Bolton, T. B., R. J. Lang, T. Takewaki, and C. D. Benham. "Patch and Whole-Cell Voltage-Clamp Studies on Single Smooth Muscle Cells." Journal of Cardiovascular Pharmacology 8 (1986): S20—S24. http://dx.doi.org/10.1097/00005344-198600088-00005.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Velte, T. J., and R. F. Miller. "Computer simulations of voltage clamping retinal ganglion cells through whole-cell electrodes in the soma." Journal of Neurophysiology 75, no. 5 (May 1, 1996): 2129–43. http://dx.doi.org/10.1152/jn.1996.75.5.2129.

Full text

Abstract:

1. Computer simulations of voltage-clamp experiments in retinal ganglion cells were implemented to better understand the insights that can be obtained with this physiological approach. 2. Simulation studies of voltage clamping were based on the contemporary approach of using whole-cell recordings with low resistance electrodes attached to the soma. Realistic ganglion cell morphologies were provided by cell staining experiments in the mudpuppy retina; selected cells included small-, medium-, and large-field neurons whose morphologies were entered into a computer through a neuron tracing program. 3. Values for the specific membrane resistance (Rm) varied from 5,000 to 100,000 omega/cm2 to conform to the range of Rm values obtained with intracellular sharp electrodes and whole-cell recordings. 4. Synaptic input currents were simulated by injecting current with and without an underlying conductance change into different regions of the dendritic tree. The time-variant waveform of the current included a combined transient and sustained component similar to the waveform of ON-bipolar activation. 5. Simulations were base on 1) intact structures, which included the soma and the entire dendritic tree, and 2) a more limited cell geometry that included representation of the soma, but only part of the dendritic tree, to represent the restricted morphology that might be rendered after cutting the retina into 150-microns cross sections for retinal slice experiments. 6. The results of this study indicate that voltage clamping from the soma, with optimal, low resistance electrodes and series resistance compensation, provides an error-free voltage clamp for slow signals that are generated within a small electrotonic distance from the soma (approximately 0.1 lambda). 7. The ideal voltage-clamp conditions are optimized when synaptic conductances are small and nonlinear membrane elements are minimally activated: small-field neurons best approximate these conditions, but clamping errors are evident in these cells when more distal branches are activated. The degree of error in voltage clamping was much greater when medium-and large-field neurons were evaluated. 8. It was not possible to clamp action potentials (nonpropagating) even when they were generated near the soma in any of the three model cells examined. 9. Experimental paradigms were developed to demonstrate that inadequate voltage clamping can lead to errors in the interpretation of experimental data when relevant variables are not taken into consideration. Suggestions are made for determining and optimizing favorable clamp conditions.

APA, Harvard, Vancouver, ISO, and other styles

10

Budai, Dénes, Lois J. Kehl, Georgetta I. Poliac, and George L. Wilcox. "An iconographic program for computer-controlled whole-cell voltage clamp experiments." Journal of Neuroscience Methods 48, no. 1-2 (June 1993): 65–74. http://dx.doi.org/10.1016/s0165-0270(05)80008-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Fransen, P. F., M. J. Demolder, and D. L. Brutsaert. "Whole cell membrane currents in cultured pig endocardial endothelial cells." American Journal of Physiology-Heart and Circulatory Physiology 268, no. 5 (May 1, 1995): H2036—H2047. http://dx.doi.org/10.1152/ajpheart.1995.268.5.h2036.

Full text

Abstract:

The whole cell mode of the patch-clamp technique was applied to cultured endocardial endothelial cells from the porcine right ventricle to study their electrophysiological properties. With isotonic pipette and bathing solutions (300-310 mosmol/kgH2O), single endocardial endothelial cells had resting membrane potentials ranging from -20 to -90 mV (mean = -55 +/- 20 mV, n = 48). In voltage-clamp experiments, the main membrane current was an inwardly rectifying K+ current with all characteristics described for the inwardly rectifying K+ current in vascular endothelium. Outward currents at positive clamp potentials were small, but when cell swelling was induced by means of a hypertonic pipette or hypotonic bathing solution and ATP (5 mM) was present in the pipette solution, a large outwardly rectifying current developed. This volume-activated current was insensitive to extracellular K+ or Na+ concentration variations but sensitive to changes in extracellular Cl- concentrations. It was inhibited in the presence of 4,4'-diisothiocyanostilbene-2,2 disulfonic acid (100-300 microM) and flufenamic acid (50-100 microM). Volume-activated Cl- channels are different from the stretch-activated cationic channels described in vascular endothelium and might be involved in the regulation of cell volume or the response to mechanical stretch.

APA, Harvard, Vancouver, ISO, and other styles

12

Yarotskyy, Viktor, John Malysz, and Georgi V. Petkov. "Properties of single-channel and whole cell Cl− currents in guinea pig detrusor smooth muscle cells." American Journal of Physiology-Cell Physiology 316, no. 5 (May 1, 2019): C698—C710. http://dx.doi.org/10.1152/ajpcell.00327.2018.

Full text

Abstract:

Multiple types of Cl− channels regulate smooth muscle excitability and contractility in vascular, gastrointestinal, and airway smooth muscle cells. However, little is known about Cl− channels in detrusor smooth muscle (DSM) cells. Here, we used inside-out single channel and whole cell patch-clamp recordings for detailed biophysical and pharmacological characterizations of Cl− channels in freshly isolated guinea pig DSM cells. The recorded single Cl− channels displayed unique gating with multiple subconductive states, a fully opened single-channel conductance of 164 pS, and a reversal potential of −41.5 mV, which is close to the ECl of −65 mV, confirming preferential permeability to Cl−. The Cl− channel demonstrated strong voltage dependence of activation (half-maximum of mean open probability, V0.5, ~−20 mV) and robust prolonged openings at depolarizing voltages. The channel displayed similar gating when exposed intracellularly to solutions containing Ca2+-free or 1 mM Ca2+. In whole cell patch-clamp recordings, macroscopic current demonstrated outward rectification, inhibitions by 4,4′-diisothiocyano-2,2′-stilbenedisulfonic acid (DIDS) and niflumic acid, and insensitivity to chlorotoxin. The outward current was reversibly reduced by 94% replacement of extracellular Cl− with I−, Br−, or methanesulfonate (MsO−), resulting in anionic permeability sequence: Cl−>Br−>I−>MsO−. While intracellular Ca2+ levels (0, 300 nM, and 1 mM) did not affect the amplitude of Cl− current and outward rectification, high Ca2+ slowed voltage-step current activation at depolarizing voltages. In conclusion, our data reveal for the first time the presence of a Ca2+-independent DIDS and niflumic acid-sensitive, voltage-dependent Cl− channel in the plasma membrane of DSM cells. This channel may be a key regulator of DSM excitability.

APA, Harvard, Vancouver, ISO, and other styles

13

Konishi, Shiro, Si-Young Song, and Koji Saito. "Neurotransmitter actions on dissociated rat sympathetic ganglion cells studied under whole-cell voltage clamp." Japanese Journal of Pharmacology 46 (1988): 103. http://dx.doi.org/10.1016/s0021-5198(19)57155-4.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Liu, S., and A. J. Mautone. "Whole cell potassium currents in fetal rat alveolar type II cells cultured on Matrigel matrix." American Journal of Physiology-Lung Cellular and Molecular Physiology 270, no. 4 (April 1, 1996): L577—L586. http://dx.doi.org/10.1152/ajplung.1996.270.4.l577.

Full text

Abstract:

Patch-clamp studies were performed on fetal rat alveolar type II cells isolated at 19 days of gestation and cultured on either plastic for 7 days or Matrigel matrix (40-50 microliters/cm2) for 10 days. Before study, cells cultured on Matrigel matrix were dissociated from alveolar-like structures with enzymes, replated, and washed with cold buffer at a constant flow rate to remove residual gel. This wash significantly improved obtaining of successful seals. Potassium current-voltage relationships and maximum whole cell K+ conductance (normalized to membrane capacitance) were significantly changed with time in cells cultured on plastic, but no significant change occurred in cells cultured on Matrigel matrix. Application of 20 mM tetraet hyl ammonium, 2mM 4-aminopyridine, and 5mM BaCl2 significantly inhibited K+ currents, showing differences in channel sensitivity to these agents and a voltage-dependent blockage between culture groups or with time in culture. To conclude, we have developed a new method by which epithelial cells cultured on Matrigel matrix can be successfully studied with the use of patch-clamp techniques. Furthermore, these studies show that fetal type II cells have voltage-activated K+ channels and that channel density and their sensitivity to channel blockers are modulated by the substratum on which the cells are cultured.

APA, Harvard, Vancouver, ISO, and other styles

15

Day, T. A., N. Orr, J. L. Bennett, and A. Pax. "Voltage-gated currents in muscle cells of Schistosoma mansoni." Parasitology 106, no. 5 (June 1993): 471–77. http://dx.doi.org/10.1017/s0031182000076769.

Full text

Abstract:

SUMMARYThree morphologically distinct types of muscle fibres isolated from the platyhelminth Schistosoma mansoni have been studied with whole cell current- and voltage-clamp techniques. Fibres showed a marked time-dependent decrease in membrane resistance in response to depolarizing current injections. Voltage-clamp experiments revealed the presence of two distinct voltage-gated outward currents. The most prominent current is a slowly activating, slowly and incompletely inactivating potassium current similar to delayed rectifier currents which have been described in a variety of cell types from a variety of organisms. Also present is a faster activating, quickly and completely inactivating potassium current that shares functional characteristics with ‘A’-currents. All three of the cell types studied possess a delayed rectifier current, but only two of the three types have ‘A’-currents. Though depolarization with high K+ leads to contraction of the dispersed fibres, no voltage-gated inward currents could be detected by whole cell voltage-clamp under any of our conditions.

APA, Harvard, Vancouver, ISO, and other styles

16

Veenstra, Richard D. "Voltage Clamp Limitations of Dual Whole-Cell Gap Junction Current and Voltage Recordings. I. Conductance Measurements." Biophysical Journal 80, no. 5 (May 2001): 2231–47. http://dx.doi.org/10.1016/s0006-3495(01)76196-6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Barros, F., G. M. Katz, G. J. Kaczorowski, R. L. Vandlen, and J. P. Reuben. "Calcium currents in GH3 cultured pituitary cells under whole-cell voltage-clamp: inhibition by voltage-dependent potassium currents." Proceedings of the National Academy of Sciences 82, no. 4 (February 1, 1985): 1108–12. http://dx.doi.org/10.1073/pnas.82.4.1108.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Garten, Matthias, Lars D. Mosgaard, Thomas Bornschlögl, Stéphane Dieudonné, Patricia Bassereau, and Gilman E. S. Toombes. "Whole-GUV patch-clamping." Proceedings of the National Academy of Sciences 114, no. 2 (December 21, 2016): 328–33. http://dx.doi.org/10.1073/pnas.1609142114.

Full text

Abstract:

Studying how the membrane modulates ion channel and transporter activity is challenging because cells actively regulate membrane properties, whereas existing in vitro systems have limitations, such as residual solvent and unphysiologically high membrane tension. Cell-sized giant unilamellar vesicles (GUVs) would be ideal for in vitro electrophysiology, but efforts to measure the membrane current of intact GUVs have been unsuccessful. In this work, two challenges for obtaining the “whole-GUV” patch-clamp configuration were identified and resolved. First, unless the patch pipette and GUV pressures are precisely matched in the GUV-attached configuration, breaking the patch membrane also ruptures the GUV. Second, GUVs shrink irreversibly because the membrane/glass adhesion creating the high-resistance seal (>1 GΩ) continuously pulls membrane into the pipette. In contrast, for cell-derived giant plasma membrane vesicles (GPMVs), breaking the patch membrane allows the GPMV contents to passivate the pipette surface, thereby dynamically blocking membrane spreading in the whole-GMPV mode. To mimic this dynamic passivation mechanism, beta-casein was encapsulated into GUVs, yielding a stable, high-resistance, whole-GUV configuration for a range of membrane compositions. Specific membrane capacitance measurements confirmed that the membranes were truly solvent-free and that membrane tension could be controlled over a physiological range. Finally, the potential for ion transport studies was tested using the model ion channel, gramicidin, and voltage-clamp fluorometry measurements were performed with a voltage-dependent fluorophore/quencher pair. Whole-GUV patch-clamping allows ion transport and other voltage-dependent processes to be studied while controlling membrane composition, tension, and shape.

APA, Harvard, Vancouver, ISO, and other styles

19

Davis, M. J., J. A. Donovitz, and J. D. Hood. "Stretch-activated single-channel and whole cell currents in vascular smooth muscle cells." American Journal of Physiology-Cell Physiology 262, no. 4 (April 1, 1992): C1083—C1088. http://dx.doi.org/10.1152/ajpcell.1992.262.4.c1083.

Full text

Abstract:

Mechanosensitive ion channels may play a key role in transducing vascular smooth muscle (VSM) stretch into active force development. To test this hypothesis, we recorded single-channel and macroscopic currents during mechanical stimulation of enzymatically dispersed vascular smooth muscle cells. Patch pipette suction activated a nonselective cation channel that was permeable to K+, Na+, and Ca2+. Whole cell stretch was accomplished using two patch-type micropipettes attached to the cell ends with suction. Stretch elicited a sustained depolarization with a magnitude similar to that observed in pressurized arteries. Under whole cell voltage clamp, stretch activated an inward current with a reversal potential near -15 mV. In another series of experiments, whole cell stretch failed to modify the current-voltage relationship for voltage-gated calcium currents. Thus, in VSM, both single-channel and whole cell data are consistent with activation of a nonselective cation channel by stretch. This mechanism may, in part, account for pressure-induced activation of intact blood vessels.

APA, Harvard, Vancouver, ISO, and other styles

20

Van Rijen, H. V. M., Ronald Wilders, Antoni C. G. Van Ginneken, and Habo J. Jongsma. "Quantitative analysis of dual whole-cell voltage-clamp determination of gap junctional conductance." Pfl�gers Archiv European Journal of Physiology 436, no. 1 (April 27, 1998): 141–51. http://dx.doi.org/10.1007/s004240050615.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Bolton, T. B., R. J. Lang, T. Takewaki, and C. D. Benham. "Patch and whole-cell voltage clamp of single mammalian visceral and vascular smooth muscle cells." Experientia 41, no. 7 (July 1985): 887–94. http://dx.doi.org/10.1007/bf01970006.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Sada, Hideaki, Takashi Ban, Takeshi Fujita, Yoshio Ebina, and Nicholas Sperelakis. "Developmental change in fast Na channel properties in embryonic chick ventricular heart cells." Canadian Journal of Physiology and Pharmacology 73, no. 10 (October 1, 1995): 1475–84. http://dx.doi.org/10.1139/y95-205.

Full text

Abstract:

To assess developmental changes in kinetic properties of the cardiac sodium current, whole-cell voltage-clamp experiments were conducted using 3-, 10-, and 17-day-old embryonic chick ventricular heart cells. Experimental data were quantified according to the Hodgkin–Huxley model. While the Na current density, as examined by the maximal conductance, drastically increased (six- to seven-fold) with development, other current–voltage parameters remained unchanged. Whereas the activation time constant and the steady-state activation characteristics were comparable among the three age groups, the voltage dependence of the inactivation time constant and the steady-state inactivation underwent a shift in the voltage dependence toward negative potentials during embryonic development. Consequently, the steady-state (window current) conductance, which was sufficient to induce automatic activity in the young embryos, was progressively reduced with age.Key words: cardiac electrophysiology, whole-cell voltage-clamp experiments, fast Na currents, heart, development, developmental changes.

APA, Harvard, Vancouver, ISO, and other styles

23

Gray, M. A., S. Plant, and B. E. Argent. "cAMP-regulated whole cell chloride currents in pancreatic duct cells." American Journal of Physiology-Cell Physiology 264, no. 3 (March 1, 1993): C591—C602. http://dx.doi.org/10.1152/ajpcell.1993.264.3.c591.

Full text

Abstract:

Using the whole cell configuration of the patch-clamp technique, we have identified an adenosine 3',5'-cyclic monophosphate (cAMP)-regulated chloride conductance in pancreatic duct cells. Basal whole cell currents in single isolated cells were very low (approximately 5 pA/pF) but could be stimulated 17-fold by elevation of intracellular cAMP. The cAMP-activated currents exhibited 1) a high chloride selectivity, 2) a near linear current-voltage relationship, 3) time and voltage independence, 4) block by 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) but not by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), and 5) an anion selectivity sequence based on permeability ratios of SCN > NO3 > Br > Cl > I > HCO3 > F > ClO4 > gluconate. Currents in single cells ran down within a few minutes; however, stable chloride currents could be recorded from duct cell clusters in which four or five cells were in electrical communication. We present evidence suggesting that these cAMP-regulated currents are carried by cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels. Physiologically, these CFTR channels act in parallel with chloride-bicarbonate exchangers to facilitate bicarbonate secretion across the apical plasma membrane of the duct cell.

APA, Harvard, Vancouver, ISO, and other styles

24

Katsuki, Hiroshi, and Hiroshi Saito. "Whole-cell voltage-clamp recordings from septo-hippocampal synapses formed In the organotypic coculture." Japanese Journal of Pharmacology 61 (1993): 341. http://dx.doi.org/10.1016/s0618-8278(19)31775-x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Caviedes, Pablo, Brian Ault, and Stanley I. Rapoport. "Replating improves whole cell voltage clamp recording of human fetal dorsal root ganglion neurons." Journal of Neuroscience Methods 35, no. 1 (October 1990): 57–61. http://dx.doi.org/10.1016/0165-0270(90)90094-v.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Wang, Xiaodong, Ludwik Fedorko, Yoshinori Marunaka, and Hugh O'Brodovich. "Whole-cell Cl− currents in a human peripheral airway epithelial cell line." Canadian Journal of Physiology and Pharmacology 71, no. 9 (September 1, 1993): 662–70. http://dx.doi.org/10.1139/y93-097.

Full text

Abstract:

We have used the whole-cell patch-clamp technique to identify and characterize Cl− currents in a cell line derived from human peripheral airway epithelium (NCI-H-441-4). The permeability sequence and relative selectivity for different anions was Br− (1.4) ~ I− (1.3) > Cl− (1.0) > F− (0.6) > gluconate (0.4) > glutamate (0.2). The current–voltage relationship displayed rectification in the outward direction. Diphenylamine-2-carboxylate (10−4 M) applied intracellularly blocked the outward-rectified current, while extracellularly applied diphenylamine-2-carboxylate had no effect on Cl− current. This current was also blocked by extracellularly applied 5-nitro-2-(3-phenylpropylamino)benzoate (NPPB), with an estimated IC50 of 15.2 μM. Dibutyryl-cyclic AMP (10−4 M) increased outward current, whereas pretreatment with 100 ng/mL pertussis toxin almost completely abolished the Cl− current. Pertussis toxin inhibition of this current could be partially reversed by dialysis of the cell interior with the activated αi–2 subunit of Gi protein. This cell line provides an opportunity to study directly the regulation of Cl− channels in cells derived from the peripheral human lung airways.Key words: chloride secretion, whole-cell patch clamp, GTP binding protein, cyclic AMP, pertussis toxins, 5-nitro-2-(3-phenylpropylamino)benzoate, diphenylamine-2-carboxylate, cell line H441.

APA, Harvard, Vancouver, ISO, and other styles

27

Schlatter, Eberhard. "Effect of various diuretics on membrane voltage of macula densa cells. Whole-cell patch-clamp experiments." Pfl�gers Archiv European Journal of Physiology 423-423, no. 1-2 (April 1993): 74–77. http://dx.doi.org/10.1007/bf00374963.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Frindt, G., H. Sackin, and L. G. Palmer. "Whole-cell currents in rat cortical collecting tubule: low-Na diet increases amiloride-sensitive conductance." American Journal of Physiology-Renal Physiology 258, no. 3 (March 1, 1990): F562—F567. http://dx.doi.org/10.1152/ajprenal.1990.258.3.f562.

Full text

Abstract:

Individual principal cells within the rat cortical collecting tubule were studied under voltage-clamp conditions using the whole-cell variation of the patch-clamp technique. Isolated tubules were split to expose the apical membrane surface and bathed in NaCl medium at 23 degrees C. When carboxyfluorescein was included in the patch pipette, the dye diffused rapidly into the cell being clamped but did not spread to neighboring cells, indicating a lack of cell-to-cell coupling. Average cell capacitance under whole-cell clamp conditions with KCl in the pipette was 18 +/- 2 pF (n = 10 cells) in rats maintained on a normal diet, consistent with that expected from morphometric measurements of cell surface area. The capacitance increased to 36 +/- 7 pF (n = 8 cells) for rats kept on a low-Na diet, indicating that cell membrane area was increased under these conditions. The amiloride-sensitive whole-cell conductance (GNa), assumed to equal the conductance through apical Na channels, was determined as the slope of the current-voltage relation near zero holding potential. GNa was 6.0 +/- 1.7 nS/cell (n = 12) for rats maintained on a low-Na diet compared with 0.06 +/- 0.08 nS/cell (n = 13) for rats kept on a normal diet. The amiloride-insensitive whole-cell conductance averaged 9.1 +/- 2.0 nS/cell, with no significant difference between low-Na and normal groups. Sodium channel density (N) was estimated from GNa, the mean open probability of the channel, and the single-channel conductance. N equals 3,000 channels/cells in rats on a low-Na diet compared with N less than 100 channels/cell for rats on a normal diet.

APA, Harvard, Vancouver, ISO, and other styles

29

Zeng, Tao, Glenna C. L. Bett, and Frederick Sachs. "Stretch-activated whole cell currents in adult rat cardiac myocytes." American Journal of Physiology-Heart and Circulatory Physiology 278, no. 2 (February 1, 2000): H548—H557. http://dx.doi.org/10.1152/ajpheart.2000.278.2.h548.

Full text

Abstract:

Mechanoelectric transduction can initiate cardiac arrhythmias. To examine the origins of this effect at the cellular level, we made whole cell voltage-clamp recordings from acutely isolated rat ventricular myocytes under controlled strain. Longitudinal stretch elicited noninactivating inward cationic currents that increased the action potential duration. These stretch-activated currents could be blocked by 100 μM Gd3+ but not by octanol. The current-voltage relationship was nearly linear, with a reversal potential of approximately −6 mV in normal Tyrode solution. Current density varied with sarcomere length (SL) according to I (pA/pF) = 8.3 − 5.0SL (μm). Repeated attempts to record single channel currents from stretch-activated ion channels failed, in accord with the absence of such data from the literature. The inability to record single channel currents may be a result of channels being located on internal membranes such as the T tubules or, possibly, inactivation of the channels by the mechanics of patch formation.

APA, Harvard, Vancouver, ISO, and other styles

30

Suzuki, K., and O. H. Petersen. "Patch-clamp study of single-channel and whole-cell K+ currents in guinea pig pancreatic acinar cells." American Journal of Physiology-Gastrointestinal and Liver Physiology 255, no. 3 (September 1, 1988): G275—G285. http://dx.doi.org/10.1152/ajpgi.1988.255.3.g275.

Full text

Abstract:

K+ channels in the plasma membrane of isolated guinea pig pancreatic acini were studied by patch-clamp single-channel and whole-cell current recording techniques. Three types of K+-permeable pores were found in excised patch experiments: Ca2+-activated nonselective cation channels with a unit conductance of approximately 25 pS that could be inhibited by ATP acting on the membrane inside, and two kinds of Ca2+- and voltage-activated K+-selective channels with unit conductances (in symmetrical K+-rich solutions) of about 200 and 30 pS, respectively. In intact cells, pentagastrin activation of currents through the 30 pS K+-selective pores was demonstrated. In these experiments pentagastrin was added to the bath solution and had no direct contact with the electrically isolated membrane area from which the single-channel currents were recorded, suggesting that the activation is mediated via an intracellular messenger system. Pentagastrin stimulation of voltage-gated K+ currents was also observed in whole-cell recording experiments. Results from these experiments suggest that in the stimulated condition the membrane electrical properties were dominated by the 30 pS K+-selective channels.

APA, Harvard, Vancouver, ISO, and other styles

31

McCann, J. D., M. Li, and M. J. Welsh. "Identification and regulation of whole-cell chloride currents in airway epithelium." Journal of General Physiology 94, no. 6 (December 1, 1989): 1015–36. http://dx.doi.org/10.1085/jgp.94.6.1015.

Full text

Abstract:

We used the whole-cell patch-clamp technique to study membrane currents in human airway epithelial cells. The conductive properties, as described by the instantaneous current-voltage relationship, rectified in the outward direction when bathed in symmetrical CsCl solutions. In the presence of Cl concentration gradients, currents reversed near ECl and were not altered significantly by cations. Agents that inhibit the apical membrane Cl conductance inhibited Cl currents. These conductive properties are similar to the conductive properties of the apical membrane Cl channel studied with the single-channel patch-clamp technique. The results suggest that the outwardly rectifying Cl channel is the predominant Cl-conductive pathway in the cell membrane. The steady-state and non-steady-state kinetics indicate that current flows through ion channels that are open at hyperpolarizing voltages and close with depolarization. These Cl currents were regulated by the cAMP-dependent protein kinase: when the catalytic subunit of cAMP-dependent protein kinase was included in the pipette solution, Cl channel current more than doubled. We also found that reducing extracellular osmolarity by 30% increased Cl current, suggesting that cell-swelling stimulated Cl current. Studies of transepithelial Cl transport in cell monolayers suggest that a reduction in solution osmolarity activates the apical Cl channel: reducing extracellular osmolarity stimulated a short-circuit current that was inhibited by Cl-free solution, by mucosal addition of a Cl channel antagonist, and by submucosal addition of a loop diuretic. These results suggest that apical membrane Cl channels may be regulated by cell volume and by the cAMP-dependent protein kinase.

APA, Harvard, Vancouver, ISO, and other styles

32

Kawai, F., T. Kurahashi, and A. Kaneko. "T-type Ca2+ channel lowers the threshold of spike generation in the newt olfactory receptor cell." Journal of General Physiology 108, no. 6 (December 1, 1996): 525–35. http://dx.doi.org/10.1085/jgp.108.6.525.

Full text

Abstract:

Mechanisms underlying action potential generation in the newt olfactory receptor cell were investigated by using the whole-cell version of the patch-clamp technique. Isolated olfactory cells had a resting membrane potential of -70 +/- 9 mV. Injection of a depolarizing current step triggered action potentials under current clamp condition. The amplitude of the action potential was reduced by lowering external Na+ concentration. After a complete removal of Na+, however, cells still showed action potentials which was abolished either by Ca2+ removal or by an application of Ca2+ channel blocker (Co2+ or Ni2+), indicating an involvement of Ca2+ current in spike generation of newt olfactory receptor cells. Under the voltage clamp condition, depolarization of the cell to -40 mV from the holding voltage of -100 mV induced a fast transient inward current, which consisted of Na+ (INa) and T-type Ca2+ (ICa.T) currents. The amplitude of ICa,T was about one fourth of that of INa. Depolarization to more positive voltages also induced L-type Ca2+ current (ICa,L). ICa,L was as small as a few pA in normal Ringer solution. The activating voltage of ICa,T was approximately 10 mV more negative than that of INa. Under current clamp, action potentials generated by a least effective depolarization was almost completely blocked by 0.1 mM Ni2+ (a specific T-type Ca2+ channel blocker) even in the presence of Na+. These results suggest that ICa,T contributes to action potential in the newt olfactory receptor cell and lowers the threshold of spike generation.

APA, Harvard, Vancouver, ISO, and other styles

33

PERES, A. "Calcium current in mouse eggs recorded with the tight-seal, whole-cell voltage-clamp technique." Cell Biology International Reports 10, no. 2 (February 1986): 117–19. http://dx.doi.org/10.1016/0309-1651(86)90095-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Ohya, Yusuke, Kenji Kitamura, and Hirosi Kuriyama. "Ca dependent K currents recorded from dispersed single smooth muscle cell using whole cell voltage clamp method." Japanese Journal of Pharmacology 40 (1986): 240. http://dx.doi.org/10.1016/s0021-5198(19)59467-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Hoshi, T., and R. W. Aldrich. "Voltage-dependent K+ currents and underlying single K+ channels in pheochromocytoma cells." Journal of General Physiology 91, no. 1 (January 1, 1988): 73–106. http://dx.doi.org/10.1085/jgp.91.1.73.

Full text

Abstract:

Properties of the whole-cell K+ currents and voltage-dependent activation and inactivation properties of single K+ channels in clonal pheochromocytoma (PC-12) cells were studied using the patch-clamp recording technique. Depolarizing pulses elicited slowly inactivating whole-cell K+ currents, which were blocked by external application of tetraethylammonium+, 4-aminopyridine, and quinidine. The amplitudes and time courses of these K+ currents were largely independent of the prepulse voltage. Although pharmacological agents and manipulation of the voltage-clamp pulse protocol failed to reveal any additional separable whole-cell currents in a majority of the cells examined, single-channel recordings showed that, in addition to the large Ca++-dependent K+ channels described previously in many other preparations, PC-12 cells had at least four distinct types of K+ channels activated by depolarization. These four types of K+ channels differed in the open-channel current-voltage relation, time course of activation and inactivation, and voltage dependence of activation and inactivation. These K+ channels were designated the Kw, Kz, Ky, and Kx channels. The typical chord conductances of these channels were 18, 12, 7, and 7 pS in the excised configuration using Na+-free saline solutions. These four types of K+ channels opened in the presence of low concentrations of internal Ca++ (1 nM). Their voltage-dependent gating properties can account for the properties of the whole-cell K+ currents in PC-12 cells.

APA, Harvard, Vancouver, ISO, and other styles

36

Zhang, Quan, Juris Galvanovskis, Fernando Abdulkader, Christopher J. Partridge, Sven O. Göpel, Lena Eliasson, and Patrik Rorsman. "Cell coupling in mouse pancreatic β-cells measured in intact islets of Langerhans." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, no. 1880 (July 16, 2008): 3503–23. http://dx.doi.org/10.1098/rsta.2008.0110.

Full text

Abstract:

The perforated whole-cell configuration of the patch-clamp technique was applied to functionally identified β-cells in intact mouse pancreatic islets to study the extent of cell coupling between adjacent β-cells. Using a combination of current- and voltage-clamp recordings, the total gap junctional conductance between β-cells in an islet was estimated to be 1.22 nS. The analysis of the current waveforms in a voltage-clamped cell (due to the firing of an action potential in a neighbouring cell) suggested that the gap junctional conductance between a pair of β-cells was 0.17 nS. Subthreshold voltage-clamp depolarization (to −55 mV) gave rise to a slow capacitive current indicative of coupling between β-cells, but not in non-β-cells, with a time constant of 13.5 ms and a total charge movement of 0.2 pC. Our data suggest that a superficial β-cell in an islet is in electrical contact with six to seven other β-cells. No evidence for dye coupling was obtained when cells were dialysed with Lucifer yellow even when electrical coupling was apparent. The correction of the measured resting conductance for the contribution of the gap junctional conductance indicated that the whole-cell K ATP channel conductance ( G K,ATP ) falls from approximately 2.5 nS in the absence of glucose to 0.1 nS at 15 mM glucose with an estimated IC 50 of approximately 4 mM. Theoretical considerations indicate that the coupling between β-cells within the islet is sufficient to allow propagation of [Ca 2+ ] i waves to spread with a speed of approximately 80 μm s −1 , similar to that observed experimentally in confocal [Ca 2+ ] i imaging.

APA, Harvard, Vancouver, ISO, and other styles

37

Sato, K., M. Ohtsuyama, and F. Sato. "Pharmacological regulation of sweat ductal function as studied by whole cell voltage/current clamp methods." Journal of Dermatological Science 6, no. 1 (August 1993): 17. http://dx.doi.org/10.1016/0923-1811(93)90847-i.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Quinn, S. J., U. Brauneis, D. L. Tillotson, M. C. Cornwall, and G. H. Williams. "Calcium channels and control of cytosolic calcium in rat and bovine zona glomerulosa cells." American Journal of Physiology-Cell Physiology 262, no. 3 (March 1, 1992): C598—C606. http://dx.doi.org/10.1152/ajpcell.1992.262.3.c598.

Full text

Abstract:

Rat and bovine adrenal zona glomerulosa (ZG) cells possess a low-threshold, voltage-dependent Ca2+ current that was characterized using whole cell voltage clamp techniques. Activation of this current is observed at membrane potentials above -80 mV with maximal peak Ca2+ current elicited near -30 mV. Inactivation of the Ca2+ current was half-maximal between -74 and -58 mV, depending on the external Ca2+ concentration and was nearly complete at -40 mV. The voltage dependency of the current indicates that a calcium current could be sustained at membrane potentials between -80 and -40 mV and thereby elevates cytosolic calcium (Cai) levels. Under basal conditions, Cai is stable in single rat ZG cells, whereas more than half of the bovine ZG cells produce repeated Cai transients. These Cai transients, which are blocked by removal of external Ca2+ or addition of Ni2+, are likely due to repetitive electrical activity in bovine ZG cells. Cai responses can be elicited by small increases in external K+ concentration (5-10 mM) in both rat and bovine ZG cells, indicating the opening of low-threshold Ca2+ channels. However, these Cai changes remain robust at high external K+ concentrations (20-40 mM). In experiments combining Cai measurements and whole cell voltage clamp, a steep dependence of Cai on membrane potential was revealed beginning at depolarizing voltages near a holding membrane potential of -80 mV. A maximal increase in Cai occurred near -30 mV (equivalent to an external K+ concentration of 40 mM), a membrane voltage at which sustained current through low-threshold Ca2+ channels should be negligible. These data raise the possibility of additional voltage-dependent pathways for Ca2+ influx.

APA, Harvard, Vancouver, ISO, and other styles

39

Gandini, María A., Alejandro Sandoval, and Ricardo Felix. "Whole-Cell Patch-Clamp Recording of Recombinant Voltage-Sensitive Ca2+ Channels Heterologously Expressed in HEK-293 Cells." Cold Spring Harbor Protocols 2014, no. 4 (April 2014): pdb.prot073213. http://dx.doi.org/10.1101/pdb.prot073213.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Imon, K., T. Amano, K. Ishihara, M. Sasa, and K. Yajin. "Existence of voltage-dependent Ca2+ channels in vestibular dark cells: cytochemical and whole-cell patch-clamp studies." European Archives of Oto-Rhino-Laryngology 254, no. 6 (June 1997): 287–91. http://dx.doi.org/10.1007/bf02905990.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Francke, M., T. Pannicke, and W. Reichelt. "Repetitive depletion and recovery of intracellular K+ in retinal Müller glial cells during whole-cell voltage-clamp." Journal of Neuroscience Methods 61, no. 1-2 (September 1995): 169–84. http://dx.doi.org/10.1016/0165-0270(95)00039-w.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Lipski, Janusz, Yoshinori Kawai, Jianguo Qi, Alison Comer, and Joe Win. "Whole cell patch-clamp study of putative vasomotor neurons isolated from the rostral ventrolateral medulla." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 274, no. 4 (April 1, 1998): R1099—R1110. http://dx.doi.org/10.1152/ajpregu.1998.274.4.r1099.

Full text

Abstract:

A distinct subpopulation of neurons in the rostral and ventrolateral part of the medulla oblongata (RVL) plays a key role in controlling sympathetic vasomotor tone. To characterize these neurons under conditions in which all cell-to-cell interactions are eliminated, RVL neurons were acutely dissociated from 13- to 19-day old rats. Cells projecting to the upper thoracic segments were retrogradely labeled with fluorescent beads. Fifty-two percent (17/33) of examined spinally projecting neurons were catecholaminergic, as demonstrated by single-cell reverse transcription-polymerase chain reaction or immunocytochemistry. No spontaneous (capacitive) spikes were revealed in the tight seal cell-attached configuration. Whole cell recordings were made from 54 spinally projecting neurons using Cs+- or K+-containing pipettes. No spontaneous firing was observed in current-clamp mode with K+-based pipettes (membrane potential, −61.5 ± 2.3 mV). Step depolarizations (300- or 400-ms pulses, up to 100 pA) evoked regular firing or one to four spikes. Several voltage-gated currents, resembling the transient and persistent Na+, delayed rectifier and low- and high-threshold Ca2+, were revealed in voltage-clamp mode. These results show that isolated spinally projecting RVL neurons display no pacemaker-like activity. Because data from the literature indicate that these neurons are capable of generating such activity under different experimental conditions, the factors responsible for different behavior need to be determined. Dissociated RVL neurons provide a useful new model for studying biophysical and other properties of neurons involved in blood pressure control.

APA, Harvard, Vancouver, ISO, and other styles

43

Stoddard, J. S., J. H. Steinbach, and L. Simchowitz. "Whole cell Cl- currents in human neutrophils induced by cell swelling." American Journal of Physiology-Cell Physiology 265, no. 1 (July 1, 1993): C156—C165. http://dx.doi.org/10.1152/ajpcell.1993.265.1.c156.

Full text

Abstract:

The properties of the conductive Cl- transport pathway underlying regulatory volume decrease (RVD) in human neutrophils were investigated using the whole cell patch-clamp technique. Cell swelling was induced during whole cell recordings by making the patch pipette solution hyperosmotic (approximately 20%) relative to the bath by addition of sucrose. Immediately after establishment of the whole cell configuration, no measurable Cl- currents were evident. Over a period of several minutes the outwardly rectifying Cl- current that developed displayed no apparent voltage dependence of activation and did not inactivate with time during voltage steps over the range of -80 to +80 mV. Reduction of Cl- currents by application of suction to the interior of the pipette implied that the swelling-induced Cl- channels are activated by membrane stretch. Based on reversal potential measurements, the volume-induced Cl- conductance was found to discriminate poorly among Cl-, Br-, I-, and NO3-, to possess a finite permeability to glucuronate (Pglucuronate/PCl approximately 0.1) and to be impermeable to cations. Single-channel conductance was estimated to be 1.5 pS from analysis of the variance of membrane current fluctuations. The activated Cl- currents were blocked by 100 microM of the compound MK-447 analogue A (inhibitor constant Ki = 37 microM) and by 200 microM 3,5-diiodosalicylate, 500 microM 4-acetamido-4'-iodothiocyanostilbene-2,2'-disulfonic acid, and 200 microM UK-5099. These results suggest that the initial event triggering RVD in neutrophils may be activation of stretch sensitive Cl- channels in the plasma membrane.

APA, Harvard, Vancouver, ISO, and other styles

44

Powers, Randall K., and Marc D. Binder. "Persistent Sodium and Calcium Currents in Rat Hypoglossal Motoneurons." Journal of Neurophysiology 89, no. 1 (January 1, 2003): 615–24. http://dx.doi.org/10.1152/jn.00241.2002.

Full text

Abstract:

Voltage-dependent persistent inward currents are thought to make an important contribution to the input–output properties of α−motoneurons, influencing both the transfer of synaptic current to the soma and the effects of that current on repetitive discharge. Recent studies have paid particular attention to the contribution of L-type calcium channels, which are thought to be widely distributed on both the somatic and the dendritic membrane. However, the relative contribution of different channel subtypes as well as their somatodendritic distribution may vary among motoneurons of different species, developmental stages, and motoneuron pools. In this study, we have characterized persistent inward currents in juvenile (10- to 24-day-old) rat hypoglossal (HG) motoneurons. Whole-cell, voltage-clamp recordings were made from the somata of visualized rat HG motoneurons in 300-μm brain stem slices. Slow (10 s), triangular voltage-clamp commands from a holding potential of −70 to 0 mV and back elicited whole-cell currents that were dominated by outward, potassium currents, but often showed a region of negative slope resistance on the rising phase of the command. In the presence of potassium channel blockers (internal cesium and external 4-aminopyridine and tetraethylammonium), net inward currents were present on both the rising and falling phases of the voltage-clamp command. A portion of the inward current present on the ascending phase of the command was mediated by TTX-sensitive sodium channels, whereas calcium channels mediated the remainder of the current. We found roughly the same relative contributions of P-, N-, and L-type channels to the calcium currents recorded at the soma that had previously been found in neonatal rat HG motoneurons. In most cells, the somatic voltage thresholds for calcium current onset and offset were similar and the peak current was largest on the ascending phase of the clamp command. However, about one-third of the cells exhibited a substantial clockwise current hysteresis, i.e., inward currents were present at lower voltages on the descending phase of the clamp command. In the same cells, 1-s depolarizing voltage-clamp commands were followed by prolonged tail currents, consistent with a prominent contribution from dendritic channels. In contrast to previous reports on turtle and mouse motoneurons, blocking L-type calcium channels did not eliminate these presumed dendritic currents.

APA, Harvard, Vancouver, ISO, and other styles

45

Moritz, Anna T., Gregory Newkirk, Randall K. Powers, and Marc D. Binder. "Facilitation of Somatic Calcium Channels Can Evoke Prolonged Tail Currents in Rat Hypoglossal Motoneurons." Journal of Neurophysiology 98, no. 2 (August 2007): 1042–47. http://dx.doi.org/10.1152/jn.01294.2006.

Full text

Abstract:

Voltage-dependent persistent inward currents (PICs) make an important contribution to the input-output properties of alpha motoneurons. PICs are thought to be mediated by membrane channels located primarily on the dendrites as evidenced by prolonged tail currents following the termination of a voltage step and by a clockwise hysteresis in the whole cell inward currents recorded in response to depolarizing then repolarizing voltage ramp commands. We report here, however, that voltage-clamp currents with these same features can be generated in isolated somatic membrane patches from rat hypoglossal motoneurons. Long-lasting (200–800 ms) tail currents after 1-s voltage-clamp pulses were observed in nucleated patches from 16 of 23 cells. Further, these somatic PICs display “facilitation” in response to conditioning depolarization as previously observed in whole cell recordings from intact neurons. Pharmacological tests suggest that the PICs were primarily mediated by Cav1 channels. Our results show that many of the features of persistent calcium currents recorded from intact motoneurons do not necessarily reflect a remote dendritic origin but can also be ascribed to the intrinsic properties of their Cav1 channels.

APA, Harvard, Vancouver, ISO, and other styles

46

Sims, S. M., and S. J. Dixon. "Inwardly rectifying K+ current in osteoclasts." American Journal of Physiology-Cell Physiology 256, no. 6 (June 1, 1989): C1277—C1282. http://dx.doi.org/10.1152/ajpcell.1989.256.6.c1277.

Full text

Abstract:

Membrane properties of freshly isolated rat osteoclasts were studied using the whole cell patch-clamp recording technique. The membrane potential could switch between two stable levels, approximately -70 and -15 mV. Voltage-clamp studies indicated that osteoclasts exhibited marked inward rectification, with hyperpolarizing voltage commands from -70 mV activating large inward currents. No voltage-dependent currents were observed in response to depolarization. An increase in external K+ concentration shifted the current-voltage relationship positive in a manner predicted for K+ current. Furthermore, barium and cesium reversibly suppressed the inward current. Thus the dominant current evident in osteoclasts was inwardly rectifying K+ current, resembling that found in a number of cell types, including cardiac and skeletal muscle and oocytes. The current-voltage relationship of osteoclasts was "N-shaped" and could intersect the zero-current level at three potentials, accounting for two stable membrane potentials. Switching of membrane potential between these two levels may regulate a number of the cellular processes involved in bone resorption.

APA, Harvard, Vancouver, ISO, and other styles

47

Lindau, M., and J. M. Fernandez. "A patch-clamp study of histamine-secreting cells." Journal of General Physiology 88, no. 3 (September 1, 1986): 349–68. http://dx.doi.org/10.1085/jgp.88.3.349.

Full text

Abstract:

The ionic conductances in rat basophilic leukemia cells (RBL-2H3) and rat peritoneal mast cells were investigated using the patch-clamp technique. These two cell types were found to have different electrophysiological properties in the resting state. The only significant conductance of RBL-2H3 cells was a K+-selective inward rectifier. The single channel conductance at room temperature increased from 2-3 pS at 2.8 mM external K+ to 26 pS at 130 mM K+. This conductance, which appeared to determine the resting potential, could be blocked by Na+ and Ba2+ in a voltage-dependent manner. Rat peritoneal mast cells had a whole-cell conductance of only 10-30 pS, and the resting potential was close to zero. Sometimes discrete openings of channels were observed in the whole-cell configuration. When the Ca2+ concentration on the cytoplasmic side of the membrane was elevated, two types of channels with poor ion specificity appeared. A cation channel, observed at a Ca2+ concentration of approximately 1 microM, had a unit conductance of 30 pS. The other channel, activated at several hundred micromolar Ca2+, was anion selective and had a unit conductance of approximately 380 pS in normal Ringer solution and a bell-shaped voltage dependence. Antigenic stimulation did not cause significant changes in the ionic conductances in either cell type, which suggests that these cells use a mechanism different from ionic currents in stimulus-secretion coupling.

APA, Harvard, Vancouver, ISO, and other styles

48

Huang, S. J., W. O. Fu, Y. W. Chung, T. S. Zhou, and P. Y. Wong. "Properties of cAMP-dependent and Ca(2+)-dependent whole cell Cl- conductances in rat epididymal cells." American Journal of Physiology-Cell Physiology 264, no. 4 (April 1, 1993): C794—C802. http://dx.doi.org/10.1152/ajpcell.1993.264.4.c794.

Full text

Abstract:

Single rat epididymal cell studied under whole cell patch-clamp condition responded to 8-(4-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (CPT-cAMP) (500 microM) and to ionomycin (1 microM) by an increase in whole cell conductance. A major part of the stimulated current was carried by Cl-, although a small part was due to nonselective cation current. After elimination of the cation current component by using impermeant cation, the cells revealed different Cl- conductance properties in response to adenosine 3',5'-cyclic monophosphate (cAMP) and ionomycin. The cAMP-stimulated Cl- conductance was independent of time and voltage and showed a linear current-voltage relationship. The anion permselectivity was NO3- > Br- > Cl- approximately I- >> SO(4)2-. The ionomycin-stimulated Cl- conductance showed marked time and voltage dependency. In contrast to the cAMP-induced anion permselectivity, the ionomycin-induced anion permselectivity was I- > Br- approximately NO3- > Cl- >> SO(4)2-. These results indicate that the epididymal epithelial cells exhibit different Cl- conductances sensitive to cAMP and Ca2+. The cAMP-activated conductance has properties resembling the type associated with the cystic fibrosis transmembrane conductance regulator found in cystic fibrosis-affected epithelia. This finding supports the notion that the epididymis is a cystic fibrosis epithelium.

APA, Harvard, Vancouver, ISO, and other styles

49

Kusano, K., and H. Gainer. "Whole cell current analyses of pancreatic acinar AR42J cells. I. Voltage- and Ca(2+)-activated currents." American Journal of Physiology-Cell Physiology 260, no. 5 (May 1, 1991): C934—C948. http://dx.doi.org/10.1152/ajpcell.1991.260.5.c934.

Full text

Abstract:

Voltage- and Ca(2+)-activated whole cell currents were studied in AR42J cells, a clonal cell line derived from rat pancreatic acinar cells, using a patch electrode voltage-clamp technique. Four kinds of ionic currents were identified by their ionic dependencies, pharmacological properties, and kinetic parameters: 1) an outward current flow due mainly to a voltage-dependent K(+)-conductance increase, 2) an initial transient inward current due to an Na(+)-conductance increase, 3) transient and long-duration inward current due to a Ca(2+)-conductance increase, and 4) a slowly activating inward current that persists over the duration of the depolarizing pulse and deactivates slowly upon repolarization, producing a slow inward tail current. The slow inward tail current was particularly robust and was interpreted as due to a Ca(2+)-activated Cl(-)-conductance increase, since 1) the generation of this current was blocked by removing the extracellular Ca2+, applying Ca(2+)-channel blockers (Cd2+, nifedipine), or by lowering the intracellular Ca2+ concentration [( Ca2+]i) with EGTA; and 2) the reversal potential (Erev) of the slow inward tail current was close to 0 mV in the control condition (152 mM [Cl-]o/154 mM [Cl-]i), and changes of the [Cl-]o/[Cl )i ratio shifted the Erev toward the predicted Cl- equilibrium potential.

APA, Harvard, Vancouver, ISO, and other styles

50

Brichta, Alan M., Anne Aubert, Ruth Anne Eatock, and Jay M. Goldberg. "Regional Analysis of Whole Cell Currents From Hair Cells of the Turtle Posterior Crista." Journal of Neurophysiology 88, no. 6 (December 1, 2002): 3259–78. http://dx.doi.org/10.1152/jn.00770.2001.

Full text

Abstract:

The turtle posterior crista is made up of two hemicristae, each consisting of a central zone containing type I and type II hair cells and a surrounding peripheral zone containing only type II hair cells and extending from the planum semilunatum to the nonsensory torus. Afferents from various regions of a hemicrista differ in their discharge properties. To see if afferent diversity is related to the basolateral currents of the hair cells innervated, we selectively harvested type I and II hair cells from the central zone and type II hair cells from two parts of the peripheral zone, one near the planum and the other near the torus. Voltage-dependent currents were studied with the whole cell, ruptured-patch method and characterized in voltage-clamp mode. We found regional differences in both outwardly and inwardly rectifying voltage-sensitive currents. As in birds and mammals, type I hair cells have a distinctive outwardly rectifying current ( IK,L), which begins activating at more hyperpolarized voltages than do the outward currents of type II hair cells. Activation of IK,Lis slow and sigmoidal. Maximal outward conductances are large. Outward currents in type II cells vary in their activation kinetics. Cells with fast kinetics are associated with small conductances and with partial inactivation during 200-ms depolarizing voltage steps. Almost all type II cells in the peripheral zone and many in the central zone have fast kinetics. Some type II cells in the central zone have large outward currents with slow kinetics and little inactivation. Although these currents resemble IK,L, they can be distinguished from the latter both electrophysiologically and pharmacologically. There are two varieties of inwardly rectifying currents in type II hair cells: activation of IK1is rapid and monoexponential, whereas that of Ihis slow and sigmoidal. Many type II cells either have both inward currents or only have IK1; very few cells only have Ih. Inward currents are less conspicuous in type I cells. Type II cells near the torus have smaller outwardly rectifying currents and larger inwardly rectifying currents than those near the planum, but the differences are too small to account for variations in discharge properties of bouton afferents innervating the two regions of the peripheral zone. The large outward conductances seen in central cells, by lowering impedances, may contribute to the low rotational gains of some central-zone afferents.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Whole Cell Voltage Clamp'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles