Littérature scientifique sur le sujet « Cationic conductance »
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Articles de revues sur le sujet "Cationic conductance":
1
Wang, Hong-Zhan, et Richard D. Veenstra. « Monovalent Ion Selectivity Sequences of the Rat Connexin43 Gap Junction Channel ». Journal of General Physiology 109, no 4 (1 avril 1997) : 491–507. http://dx.doi.org/10.1085/jgp.109.4.491.
Résumé :
The relative permeability sequences of the rat connexin 43 (rCx43) gap junction channel to seven cations and chloride were examined by double whole cell patch clamp recording of single gap junction channel currents in rCx43 transfected neuroblastoma 2A (N2A) cell pairs. The measured maximal single channel slope conductances (γj, in pS) of the junctional current-voltage relationships in 115 mM XCl were RbCl (103) ≥ CsCl (102) > KCl (97) > NaCl (79) ≥ LiCl (78) > TMACl (65) > TEACl (53) and for 115 mM KY were KBr (105) > KCl (97) > Kacetate (77) > Kglutamate (61). The single channel conductance-aqueous mobility relationships for the test cations and anions were linear. However, the predicted minimum anionic and cationic conductances of these plots did not accurately predict the rCx43 channel conductance in 115 mM KCl. Instead, the conductance of the rCx43 channel in 115 mM KCl was accurately predicted from cationic and anionic conductance-mobility plots by applying a mobility scaling factor Dx/Do, which depends upon the relative radii of the permeant ions to an estimated pore radius. Relative permeabilities were determined for all of the monovalent cations and anions tested from asymmetric salt reversal potential measurements and the Goldman-Hodgkin-Katz voltage equation. These experiments estimate the relative chloride to potassium permeability to be 0.13. The relationship between the relative cation permeability and hydrated radius was modeled using the hydrodynamic equation assuming a pore radius of 6.3 ± 0.4 Å. Our data quantitatively demonstrate that the rCx43 gap junction channel is permeable to monovalent atomic and organic cations and anions and the relative permeability sequences are consistent with an Eisenman sequence II or I, respectively. These predictions about the rCx43 channel pore provide a useful basis for future investigations into the structural determinants of the conductance and permeability properties of the connexin channel pore.
2
Tsunenari, T., Y. Hayashi, M. Orita, T. Kurahashi, A. Kaneko et T. Mori. « A quinine-activated cationic conductance in vertebrate taste receptor cells. » Journal of General Physiology 108, no 6 (1 décembre 1996) : 515–23. http://dx.doi.org/10.1085/jgp.108.6.515.
Résumé :
The chincona alkaloid quinine is known to be a bitter tasting substance for various vertebrates. We examined the effects of quinine on isolated taste receptor cells from the bullfrog (Rana catesbeiana). Membrane currents were recorded by whole-cell recording, while quinine hydrochloride was applied extracellularly from a puffer pipette. At the resting potential (-77 +/- 9 mV, mean +/- SD, n = 49 cells), taste cells generated inward currents in response to quinine stimulation (> 1 mM), indicating a depolarizing response in the taste cells. Two types of current responses were observed; a newly found quinine-activated cationic conductance and a previously reported blocking effect of quinine on K+ conductances. The cationic current was isolated from the K+ current by using a Cs(+)-containing patch pipette. The relative permeabilities (Pion) of the quinine-activated cationic conductance were: PNa/PK/PCs = 1:0.5:0.42. The quinine dose-response relation was described by the Hill equation with the K1/2 of 3.6 mM and Hill coefficient of 5.3. When extracellular [Ca2+] (1.8 mM) was reduced to nominally free, the conductance was enhanced by about sixfold. This property is consistent with observations on quinine responses recorded from the gustatory nerve, in vivo. The quinine-induced cationic current was decreased with an application of 8-bromo-cAMP. We conclude that the bitter substance quinine activates a cation channel in taste receptor cells and this channel plays an important role in bitter taste transduction.
3
Tzan, C. J., J. R. Berg et S. A. Lewis. « Modification of epithelial permeability by cationic polypeptides ». American Journal of Physiology-Cell Physiology 265, no 6 (1 décembre 1993) : C1637—C1647. http://dx.doi.org/10.1152/ajpcell.1993.265.6.c1637.
Résumé :
It has been demonstrated that protamine sulfate (PS; a cationic polypeptide composed of 70% arginine) increases the apical membrane conductance of the mammalian urinary bladder. In this report, synthetic cationic polypeptides (CpP; e.g., polyarginine) were used to determine whether the response of the bladder to PS was due to its cationic nature (i.e., its arginine content). We demonstrate that CpP induce a large increase in the cation and anion conductance of the apical membrane of the rabbit urinary bladder epithelium. The modulation of the membrane conductance by CpP is dependent upon a number of parameters. 1) The magnitude of the conductance change was voltage dependent. 2) An increase in the total charge per molecule increased the rate of conductance change. 3) An increase in the charge density (ratio of charged amino acids to total amino acids) increased the rate of change of conductance. 4) La3+ inhibited the ability of CpP to alter the membrane conductance. 5) The rate of reversal of the CpP-induced conductance was dependent upon the total charge per molecule as well as the charge density. 6) The level of self-inhibition (ability of solution CpP to inhibit the CpP-induced membrane conductance) was inversely correlated with the charge density and was also concentration dependent, with less inhibition occurring at low mucosal CpP concentrations. These data are consistent with a model developed to describe the effect of PS on the conductive properties of the urinary bladder epithelium.
4
Tzan, C. J., J. R. Berg et S. A. Lewis. « Mammalian urinary bladder permeability is altered by cationic proteins : modulation by divalent cations ». American Journal of Physiology-Cell Physiology 267, no 4 (1 octobre 1994) : C1013—C1026. http://dx.doi.org/10.1152/ajpcell.1994.267.4.c1013.
Résumé :
It was previously demonstrated that protamine sulfate (PS, a cationic polypeptide) as well as synthetic cationic polypeptides (CpP, e.g., polylysine and polyarginine) caused an increase in the apical membrane conductance of the mammalian urinary bladder epithelium that was voltage dependent. The membrane conductance induced by these CpP was mediated by a saturable binding site and was partially blocked by CpP (self-inhibition). The PS-induced membrane conductance can be modified by polyvalent cations at three sites. The first site was to competitively inhibit the interaction of PS with an apical membrane binding site. The second site was to reversibly block the conductance induced by PS. The relative binding affinity (block of PS-induced conductance) sequence was as follows: UO2(2+) > La3+ > Mn2+ > Ba2+ > or = Ca2+ > Sr2+. Although La3+, Mn2+, Ba2+, Ca2+, and Sr2+ inhibited > or = 81% of the PS-induced conductance, UO2(2+) inhibited only 51% and Mg2+ was without effect. The third site was to increase the rate of loss of the PS-induced conductance from the apical membrane. Although neither carbodiimides (carboxyl group reactive reagents) nor neuraminidase (cleaves sialic acid residues) altered the effect of PS on the urinary bladder conductance, PS increased the conductance of lipid bilayers composed of negatively charged phospholipids. A candidate for the binding site might be the negatively charged phosphate groups of membrane lipids.
5
Fologea, Daniel, Eric Krueger, Steve Rossland, Sheenah Bryant, Wylie Foss et Tyler Clark. « Cationic Polymers Inhibit the Conductance of Lysenin Channels ». Scientific World Journal 2013 (2013) : 1–8. http://dx.doi.org/10.1155/2013/316758.
Résumé :
The pore-forming toxin lysenin self-assembles large and stable conductance channels in natural and artificial lipid membranes. The lysenin channels exhibit unique regulation capabilities, which open unexplored possibilities to control the transport of ions and molecules through artificial and natural lipid membranes. Our investigations demonstrate that the positively charged polymers polyethyleneimine and chitosan inhibit the conducting properties of lysenin channels inserted into planar lipid membranes. The preservation of the inhibitory effect following addition of charged polymers on either side of the supporting membrane suggests the presence of multiple binding sites within the channel's structure and a multistep inhibition mechanism that involves binding and trapping. Complete blockage of the binding sites with divalent cations prevents further inhibition in conductance induced by the addition of cationic polymers and supports the hypothesis that the binding sites are identical for both multivalent metal cations and charged polymers. The investigation at the single-channel level has shown distinct complete blockages of each of the inserted channels. These findings reveal key structural characteristics which may provide insight into lysenin’s functionality while opening innovative approaches for the development of applications such as transient cell permeabilization and advanced drug delivery systems.
6
Zholos, A. V., et T. B. Bolton. « Effects of protons on muscarinic receptor cationic current in single visceral smooth muscle cells ». American Journal of Physiology-Gastrointestinal and Liver Physiology 272, no 2 (1 février 1997) : G215—G223. http://dx.doi.org/10.1152/ajpgi.1997.272.2.g215.
Résumé :
Effects of extracellular protons on muscarinic receptor-evoked cationic current (Icat) in single guinea pig ileal smooth muscle cells were studied by use of patch-clamp techniques: intracellular pH and pCa were buffered to 7.4 and 7.0, respectively, symmetrical 124 mM Cs+ solutions were used, and divalent cations were removed from the bathing solution. Increasing extracellular pH (pHo) from 7.4 to 8.4 caused a 16-mV parallel negative shift of the activation curve for Icat evoked by guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) with an increase in the maximal conductance and slowed Icat relaxation on hyperpolarization; acidification to pHo 6.4 produced equivalent but opposite effects. Carbachol- and GTPgammaS-activated Icat behaved similarly, suggesting that the cationic channel rather than the muscarinic receptor was the major site of action. From 11.4 to 4.4 pHo, maximal cationic conductance was reduced progressively, and the activation curve shifted positively. Na+, K+, Ca2+, and Mg2+ had complex interactions with pHo-induced effects considered to be attributable to interaction of protons with fixed negative surface charges and, at positive potentials, to channel block.
7
Kleine, T. J., A. Gladfelter, P. N. Lewis et S. A. Lewis. « Histone-induced damage of a mammalian epithelium : the conductive effect ». American Journal of Physiology-Cell Physiology 268, no 5 (1 mai 1995) : C1114—C1125. http://dx.doi.org/10.1152/ajpcell.1995.268.5.c1114.
Résumé :
Human semen has been reported to be cytotoxic to rat descending colon by a mechanism involving polyamines (cationic molecules) and collagenase. In this study, we report that histones, cationic proteins found in human semen, can contribute to semen's cytotoxicity. Histones H1, H4, and H5, when added to the mucosal side of rabbit urinary bladder epithelium, were found to alter the transepithelial conductance (Gt) in a voltage-sensitive manner. When the cell interior was negative, the conductance rapidly increased and plateaued. When the cell interior was positive, the induced conductance decreased to control values. Histone increased the Gt by increasing the apical membrane conductance rather than the tight junction conductance. The magnitude of the Gt increase was dose dependent, and the histone-induced conductance was nonselective for Na+, K+, and Cl-. The induced conductance could be reversed by either increasing mucosal Ca2+ concentration or by removal of histone from the mucosal solution. Prolonged exposure of the epithelium to histone was toxic as determined by the irreversible loss of transepithelial resistance. These results indicate that histone increases membrane ionic permeability, is cytotoxic, and thus may contribute to human semen's toxic effect on colonic epithelium.
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Queiroga, Claudiene M. de, Geovani S. de Lima, Rafaela A. F. Torres, Francisco J. da S. Paiva, Lauriane A. dos A. Soares et Hans R. Gheyi. « Formation of guava seedlings under irrigation with water of different cationic natures and salicylic acid ». Revista Caatinga 36, no 3 (septembre 2023) : 650–62. http://dx.doi.org/10.1590/1983-21252023v36n318rc.
Résumé :
ABSTRACT The objective of this study was to evaluate gas exchange, biomass, and quality of guava seedlings as a function of the cationic nature of the water used in irrigation and foliar application of salicylic acid. The experiment was carried out in a greenhouse in Pombal, PB, Brazil, using a randomized block design, in a 6 × 4 factorial scheme with six cationic compositions of irrigation water [S1 - Control (supply water); S2 - Na+; S3 - Ca2+; S4 - Na++Ca2+; S5 - Mg2+, and S6 - Na++Ca2++Mg2+], associated with four concentrations of salicylic acid (0, 1.3, 2.6, and 3.9 mM), with 3 replicates. Plants in control (S1) were irrigated with water of electrical conductivity (ECw) of 0.3 dS m-1, while in the other treatments were irrigated with different types of water and had an ECw of 4.3 dS m-1, consisting of different cations, in the form of chloride. In the seedling formation phase, guava plants were sensitive to calcic water, which resulted in a marked decrease in their growth. Stomatal conductance, transpiration, and biomass accumulation of guava seedlings were more affected by variation in electrical conductivity than by cationic nature of the water. Salicylic acid at concentrations of 2.9 and 1.9 mM increased stomatal conductance and stem dry biomass, respectively, of guava seedlings. Water with ECw of 4.3 dS m-1 allowed the formation of guava seedlings with acceptable quality for transplanting to the field, regardless of the cationic nature of the water.
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Jin, Nan Ge, Sang Don Koh et Kenton M. Sanders. « Caffeine inhibits nonselective cationic currents in interstitial cells of Cajal from the murine jejunum ». American Journal of Physiology-Cell Physiology 297, no 4 (octobre 2009) : C971—C978. http://dx.doi.org/10.1152/ajpcell.00155.2009.
Résumé :
Interstitial cells of Cajal (ICC) discharge unitary potentials in gastrointestinal muscles that constitute the basis for pacemaker activity. Caffeine has been used to block unitary potentials, but the ionic conductance responsible for unitary potentials is controversial. We investigated currents in cultured ICC from murine jejunum that may underlie unitary potentials and studied the effects of caffeine. Networks of ICC generated slow wave events under current clamp, and these events were blocked by caffeine in a concentration-dependent manner. Single ICC generated spontaneous transient inward currents (STICs) under voltage clamp at −60 mV and noisy voltage fluctuations in current clamp. STICs were unaffected when the equilibrium potential for Cl− ( ECl) was set to −60 mV (excluding Cl− currents) and reversed at 0 mV, demonstrating that a nonselective cationic conductance, and not a Cl− conductance, is responsible for STICs in ICC. Caffeine inhibited STICs in a concentration-dependent manner. Reduced intracellular Ca2+ and calmidazolium (CMZ; 1 μM) activated persistent inward, nonselective cation currents in ICC. Currents activated by CMZ and by dialysis of cells with 10 mM BAPTA were also inhibited by caffeine. Excised inside-out patches contained channels that exhibited spontaneous openings, and resulting currents reversed at 0 mV. Channel openings were increased by reducing Ca2+ concentration from 10−6 M to 10−8 M. CMZ (1 μM) also increased openings of nonselective cation channels. Spontaneous currents and channels activated by CMZ were inhibited by caffeine (5 mM). The findings demonstrate that the Ca2+-inhibited nonselective cation channels that generate STICs in ICC are blocked directly by caffeine. STICs are responsible for unitary potentials in intact muscles, and the block of these events by caffeine is consistent with the idea that a nonselective cation conductance underlies unitary potentials in ICC.
10
Lee, H. K., C. W. Shuttleworth et K. M. Sanders. « Tachykinins activate nonselective cation currents in canine colonic myocytes ». American Journal of Physiology-Cell Physiology 269, no 6 (1 décembre 1995) : C1394—C1401. http://dx.doi.org/10.1152/ajpcell.1995.269.6.c1394.
Résumé :
The mechanism of tachykinin-induced excitation was studied in isolated colonic muscle cells and intact muscle strips. In whole cell voltage-clamp studies performed at 33 degrees C, neurokinin A (NKA) and substance P (SP) reduced L-type Ca2+ current. NKA and SP activated a cationic current that reversed near 0 mV. This current (INKA or ISP, respectively) had properties similar to the acetylcholine (ACh)-activated nonselective cation conductance (IACh), activated by muscarinic stimulation in other gastrointestinal smooth muscle cells. INKA and ISP were decreased when external Na+ was reduced. In contrast to IACh, INKA and ISP were not facilitated by increases in internal Ca2+, but little or no current was activated by these peptides when extracellular Ca2+ was low. INKA (10(-7) M) and ISP (10(-5) M) were blocked by Cd2+ (5 x 10(-4) M), quinine (10(-3) M), and the tachykinin-receptor antagonist [D-Pro2,D-Trp7,9]SP (10(-5) M). Current clamp recordings and intracellular recordings of intact tissues showed that NKA and SP depolarized the cell membrane, which is consistent with the activation of a nonselective cation conductance. These data suggest that a primary mechanism of the tachykinins is to activate a nonselective cation conductance that leads to depolarization. The increase in Ca2+ entry due to tachykinin stimulation appears to be secondary to the activation of the nonselective cation conductance.
Thèses sur le sujet "Cationic conductance":
1
Hatem, Aline. « Characterization of cationic conductance in Red Blood Cells ; insights from pharmacological and pathophysiological studies ». Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS008.
Résumé :
Au cours de leur vie, les érythrocytes circulent dans tout le corps pour transporter les gaz respiratoires et remplir leurs autres fonctions. Par conséquent, les érythrocytes doivent être capable de se déformer correctement pour circuler dans tous les vaisseaux, y compris les plus petits capillaires. Cette capacité est régie par un réseau complexe associant les protéines de la membrane et du cytosquelette combiné à un rapport surface-volume finement ajusté, permettant ainsi des changements de forme instantanés pour permettre un transit rapide des GR. Cela montre à quel point il est important de maintenir le volume cellulaire pour assurer 120 jours dans la circulation. Le volume cellulaire ou l'état d'hydratation est directement influencé par l'activité des transporteurs membranaires, des pompes et des canaux ioniques. La perméabilité des érythrocytes, dominée par le mouvement des anions pour des raisons physiologiques, implique que le mouvement des cations doit être maintenu aussi bas que possible pour éviter toute modification du volume cellulaire. Cependant, dans de nombreuses conditions physiopathologiques, la perméabilité aux cations est connue pour être dérégulée, conduisant à une augmentation des niveaux intracellulaires de Ca2+ et de Na+. L'objectif de ma thèse était de mieux caractériser le rôle des canaux cationiques non sélectifs (PIEZO1, TRPV2) et du canal Gárdos dans ces conditions physiopathologiques. Des expériences ont été réalisées sur des érythrocytes issus de donneurs sains ou de patients souffrant de différentes pathologies telles que la drépanocytose, la xérocytose et la stomatocytose, en utilisant des méthodes électrophysiologiques (MBE et patch-clamp), des mesures semi-quantitatives des mouvements de Ca2+ (cytométrie en flux et imagerie cellulaire) combinées à la mesure de paramètres morphométriques, ainsi que des mesures du volume cellulaire et des contenus en ions. Dans deux études indépendantes utilisant du sang de patients drépanocytaires, nous avons pu démontrer d'une part le rôle central de l'activation de PIEZO1 dans l'augmentation de la propension à la falciformation. D'autre part, nous avons démontré une sensibilité augmentée des GR drépanocytaires à la stimulation par le THC via l'activation du TRPV2. Parallèlement à ces résultats publiés, nous avons contribué à la caractérisation fonctionnelle de nombreux variants de PIEZO1 et de KCNN4, pour lesquels nous avons conçu une série d'expériences fonctionnelles afin de mieux décrire les variants génétiquement identifiés. Cette partie avec 5 variants Gárdos et 10 variants PIEZO1 apporte des éléments fonctionnels quant à la pathogénicité des mutations identifiées et souvent classées comme des variants de signification incertaine (VUS) par les algorithmes génétiques. Nous avons également pu démontrer que la molécule Dooku1, décrite dans la littérature comme un inhibiteur des effets de Yoda1, est en fait un activateur direct de PIEZO1 dans le globule rouge, contribuant à une pharmacologie plus précise de PIEZO1. En outre, nous avons mené une série d'expériences chez des patients traités à l'Alectinib (un traitement contre le cancer du poumon), pour lesquels on observe une anémie fréquente associée à une déshydratation cellulaire. L'ensemble de ces expériences a contribué à la compréhension des perméabilités aux cations dans des conditions physiologiques et physiopathologiques. Enfin, tous ces résultats remettent en évidence la particularité des GR en ce qui concerne la perméabilité cationique et les propriétés biophysiques des membranes par rapport à d'autres types de cellules et, plus important encore, lorsque des voies mécanosensibles sont impliquées dans de tels mouvements d'ionsOver their lifespan, erythrocytes circulate throughout the body to carry respiratory gases and perform their other functions. Therefore, erythrocytes must deform properly to circulate in all vessels, including the smallest of the capillaries. This ability is governed by a complex membrane-cytoskeleton network combined with a finely tuned surface-volume ratio that allows instantaneous shape changes to enable rapid RBC transit. This highlights how important it is to maintain cell volume to ensure a 120-day journey without the possibility of repair. Cell volume or hydration status is directly influenced by the activity of membrane transporters, pumps, and ion channels. The permeability of erythrocytes, which is dominated by anion movement for physiological reasons, implies that cation movement should be kept as low as possible to avoid any change in cell volume. However, in many pathophysiological conditions, cation permeabilities are known to be deregulated, leading to increased intracellular Ca2+ and Na+ levels. My thesis aimed to better characterize the role of non-selective cation (NSC) channels (PIEZO1, TRPV2), and Gárdos channel in such pathophysiological conditions. Experiments were carried out on healthy erythrocytes as well as on cells from patients suffering from different pathologies like Sickle Cell Disease (SCD), xerocytosis, and stomatocytosis, using electrophysiological methods (MBE and patch-clamp), Ca2+ movements semi-quantification (flow cytometry and live-cell imaging) combined with the measurement of morphometric parameters, and the measurements of intracellular cell volume and other ions contents. In two independent studies using blood from sickle cell patients, we were able to demonstrate from one part the central role of PIEZO1 activation in the enhancement of sickling propensity. In the other part, we demonstrated the increased sensitivity of sickle cells to THC stimulation via TRPV2 activation. Along with these published results, we have contributed to the functional characterization of many PIEZO1 and KCNN4 variants, for which we have designed a series of functional experiments to better describe the genetically identified variants. This part with 5 Gárdos and 10 PIEZO1 variants increases the knowledge about the pathogenicity of the identified mutations, often characterized as variants of uncertain significance (VUS). We were also able to demonstrate that Dooku1, a chemical compound described in the literature as an inhibitor of Yoda1's effects, is in fact, a direct activator of PIEZO1 in erythrocytes, contributing to a more accurate pharmacology of PIEZO1. Furthermore, we conducted a series of experiments in patients treated with Alectinib (a lung cancer treatment), for which frequent anemia associated with cell volume dehydration is observed. Taken together, these studies contribute to the understanding of cation permeabilities under physiological and pathophysiological conditions. Finally, all these results highlight the particularity of RBCs regarding cationic permeability and biophysical membrane properties compared to other cell types and, more importantly when mechanosensitive pathways are involved in such ion movements
2
Livesey, Matthew Robert. « Molecular determinants of single channel conductance and ion selectivity in cationic Cys-loop receptor channels ». Thesis, University of Dundee, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510623.
3
Manandhar, Prakash. « Understanding the Functional Group-dependent Self-assembly and Cellular Entry of Cationic Conjugated Polymer Nanoparticles ». FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3673.
Résumé :
Highly fluorescent conjugated polymers (CPs) are an important class of biomaterials used for various biological applications including labelling, sensing, and delivery of biological substances. Synthetic versatility and tunable emission make CPs a superior class of biomaterials. Understanding the structure-function relationship of CPs plays a vital role in designing high performing biomaterials. The cationic CPs are self-assembled to conjugated polymer nanoparticles (CPNs) in an aqueous environment due to their amphiphilicity. The physical and biophysical properties of CPNs are highly dependent on the chemical functionality and backbone structure of CPs. Modulation of the surface property and backbone structure of CPNs play an important role for efficient internalization of CPNs into cells. The goal of this dissertation is to understand the structure function relationship of CPNs in an aqueous environment and the change in their photo physical properties upon the self-assembly of CPNs with different backbone structure upon complexation with biologically significant polysaccharides and cell membrane.
This work presents the self-assembly of a set of four cationic CPs with different connectivity and backbone structure upon complexation with a linear polyanion hyaluronic acid (HA). The study of photo physical properties changes upon the complexation with series of Glycosaminoglycans (GAGs) provides more insight about how the self-assembly behavior of cationic CPs changes upon the exposure to negatively charged polysaccharides. The understanding of the self-assembly of CPNs with negatively charged biologically important macromolecules under in vitro conditions can give us an idea of photophysical property changes of CPNs during the treatment of CPNs in the cellular environment. The study of the interaction of CPNs with cell membranes using scanning ion conductance microscopy (SICM)-based topography, potential mapping, and confocal microscopy imaging is presented. CPNs are able to induce transient pore like feature formation on the cell membrane during the cellular internalization process. A comparative study of cellular labelling and delivery of siRNA of five CPNs with guanidine motif is presented. The subcellular localization and delivery of siRNA were dependent on the side chain hydrophilicity. The CPNs fabricated with hydrophilic aminoethoxyethanol possesses excellent cellular imaging with higher siRNA delivery.
4
Monedero, Alonso David. « Characterization of cationic conductances of human erythrocytes and their involvement in health and disease ». Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS554.
Résumé :
La membrane des globules rouges est dotée de plusieurs canaux ioniques. Normalement silencieux, ils peuvent dissiper rapidement les gradients ioniques une fois activés. Lors de cette étude, l'utilisation du NS3623 à des concentrations supérieures à celles requises pour l'inhibition des voies de conductances anioniques montre que ce composé active les canaux cationiques non sélectifs permettant ainsi leur étude y compris en conditions hyperpolarisantes. Le suivi en temps réel du potentiel membranaire à l'aide de l'ionophore à protons CCCP permet d’observer directement l'activité des canaux ioniques lorsque leur ouverture modifie le potentiel membranaire. Cette méthode a été utilisée pour décrire l'homéostasie cationique dysfonctionnelle dans des cellules de patients affectés par différentes mutations sur les canaux Gárdos ou Piezo1. Elle pourrait constituer un outil de diagnostic alternatif. L'activité des canaux ioniques a été caractérisée tout au long de la période de stockage réglementaire des globules rouges stockés à 4 °C (42 jours), afin de mieux comprendre les lésions de stockage. Il a été démontré que l’activité du NSC augmentait avec le temps, devenant spectaculaire la dernière semaine de stockage. En conclusion, les canaux cationiques non sélectifs jouent un rôle dans l'homéostasie des globules rouges matures. Ils contribuent ou peuvent constituer l'origine de la fuite de cations. Ils sont à l'origine de maladies en cas de dysfonctionnement et la compréhension de leur fonctionnement dans ces conditions peut fournir des stratégies thérapeutiques. Enfin, ils sont impliqués dans les lésions de stockage compromettant par leur activité l'efficacité transfusionnelleRed cell membranes are endowed with several ion channels. Normally silent, they will rapidly dissipate ionic gradients once activated. I present a pharmacological means (NS3623) for the enhancement of NSC channels in hyperpolarizing conditions with concomitant chloride conductance inhibition in freshly drawn healthy mature RBCs. Membrane potential estimation aided by proton ionophore CCCP allows the recording of membrane potential changes in real time, enabling the observation of ion channel activity as their opening alters the membrane potential. This method was used to describe dysfunctional cation homeostasis in hereditary anemia using patient cells affected by different mutations on Gárdos or Piezo1 channels. The technique is fast, reliable and inexpensive providing an alternative diagnostic tool with the added advantage of producing ion channel activity information. Ion channel activity was characterized throughout 42-day storage period of RBCs stored at 4 C in CPD-SAGM according to French regulations to address the issue of storage lesions, which reduce transfusion efficacy. NSC activity was shown to increase over time during storage and dramatic ion channel activity was observed during the last week. Consequently, NSC activity may jeopardize cell volume and morphology upon reinfusion. In conclusion, Non-Selective Cation channels play an important role in mature RBCs. They contribute or may constitute the origin of cation leak. They cause disease when malfunctioning and insight into their operation in these conditions may supply with therapeutic strategies. They are involved in the storage lesion, and may account for RBCs demise once back in the circulation
5
Aromolaran, Ademuyiwa. « Modulation of the noradrenaline evoked non selective cation conductance in rabbit portal vein smooth muscle cells ». Thesis, St George's, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249370.
6
Takeda, Yukari. « Calcium sensitive non-selective cation conductances expressed in interstitial cells of cajal of the gastric antrum ». abstract and full text PDF (free order & ; download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3289448.
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Voss, Andrew Alvin. « Structural and functional analysis of the ryanodine receptor : multiple conductance states regulated by allosteric cation interactions and the identification of hyperreactive sulfhydryls / ». For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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AGUENAOU, HASSAN. « L'absorption du c1**(-) et du na**(+) a travers la bordure en brosse de l'intestin de la truite salmo gairdneri, r ». Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13072.
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Weatherholt, Riley Madison. « Road Salt Runoff into Freshwater Wetlands : Trends in SpecificConductance and Ion Concentration ». Kent State University Honors College / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1557152479759316.
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« TRPV4-TRPC1- BKca tri-complex mediates epoxyeicosatrienoic acid-induced membrane hyperpolarization ». Thesis, 2011. http://library.cuhk.edu.hk/record=b6075501.
Résumé :
Ma, Yan."Ca" in the title is subscript.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references (leaves 143-166).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
Chapitres de livres sur le sujet "Cationic conductance":
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Schild, Detlev. « Ciliary Cation Conductances in Olfactory Receptor Cells of the Clawed Toad Xenopus laevis ». Dans Nonselective Cation Channels, 165–71. Basel : Birkhäuser Basel, 1993. http://dx.doi.org/10.1007/978-3-0348-7327-7_12.
2
Hartmann, Lissy M., Alvaro Garcia, Evelyne Deplazes et Charles G. Cranfield. « Determining the Pore Size of Multimeric Peptide Ion Channels Using Cation Conductance Measures of Tethered Bilayer Lipid Membranes ». Dans Methods in Molecular Biology, 81–92. New York, NY : Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1843-1_7.
3
Cheng, Seng Hing, John Marshall, Ronald K. Scheule et Alan E. Smith. « [52] Cationic lipid formulations for intracellular gene delivery of cystic fibrosis transmembrane conductance regulator to airway epithelia ». Dans Methods in Enzymology, 697–717. Elsevier, 1998. http://dx.doi.org/10.1016/s0076-6879(98)92054-7.
4
Lerma, J., A. V. Paternain, N. Salvador, F. Somohano, M. Morales, et M. Casado. « Excitatory amino acid-activated channels ». Dans Ion Channel Pharmacology, 399–421. Oxford University PressOxford, 1998. http://dx.doi.org/10.1093/oso/9780198523604.003.0018.
Résumé :
Abstract Besides the widespread metabolic function, it is now well established that the dicarboxylic amino acid glutamate plays a major role in excitatory synaptic transmission. Glutamate interacts with receptors forming cationic channels with different ion permeabilities, conductances, and activation-deactivation kinetics, as well as demonstrating distinct pharmacological properties.
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Chiamulera, C., et F. Ferraguti. « Introduction ». Dans Guidebook to Protein Toxins and Their Use in Cell Biology, 247–48. Oxford University PressOxford, 1997. http://dx.doi.org/10.1093/oso/9780198599555.003.0090.
Résumé :
Abstract AMPA-kainate receptors generally conduct monovalent cations, however, glutamate in certain neuronal cells can trigger the activation of Ca2+-permeable AMPA-kainate receptors. The different ionic selectivity depends on the combination of different subunits, and in particular on the presence of the GluR2 subunit. This subunit contains an arginine residue within the second transmembrane segment, whereas the other three subunits carry a glutamine residue at the corresponding position. This difference confers a very weak Ca2+ permeability thus determining the channel conductance and Ca2+ permeation (Verdoorn et al. 1991).
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Ahmed, Waqas, et Maqsood Ahmad. « Comparative Study of Resistivity Models and Waxman Smits Model in Cooper Basin South Australia-Murteree Shale : Case Study ». Dans Unconventional Methods for Geoscience, Shale Gas and Petroleum in the 21st Century. IOS Press, 2023. http://dx.doi.org/10.3233/aerd230024.
Résumé :
Murteree organic shale are one of most rich unconventional gas reservoirs in Cooper Basin, South Australia. In shale gas reservoirs, estimation of water saturation and porosity are very erroneous when calculated from the well logs. In Roseneath and Murteree shales of Copper Basin in South Australia, we investigated their fluids contents using Archie model, Simandoux, Indonesian and Dual water model. Later, brine estimation from Waxman-Smits was correlated with Archie, Simandox, Indonesian and Dual water model results. Due to presence of high amount of clay minerals, conductivity and clay bound water are very high, the changes in salinity level of the brine due to post depositional features, followed by physical and chemical changes effect the determination of water saturation consequently. High clay volume in shale gas reservoirs cause over estimation of water saturation when determined by Archie and other resistivity models. Waxmans-Smiths equation gives more reliable results because it accounts the cation exchange capacity and conductance of clay minerals present in the formation. Also it is noticed that as the clay mineralogy percentage, clay bound water also increases with same pattern respectively. In this paper, description of Waxmans-smith equation in determination of water saturation has been presented and also relation between clay minerals and clay bound water has been discussed. Form our analysis, it has been estimated that, Waxmans-Smit conductivity model gives estimation of water more reliable as compare to resistivity models like Archie, Simandoux and Indonesian in unconventional shale gas reservoir. Hydrocarbon potential are present with respect to water saturation and resistivity logs.
Actes de conférences sur le sujet "Cationic conductance":
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Kotliarova, Anna, Olena Kotyk, Nataliia Ivanushkina, Kateryna Ivanko, Veronika Lukianenko, Bogdan Zadokha et Igor Nesteruk. « Preliminary Statistical Analysis of Large Conductance Cationic Channels Flickering ». Dans 2020 IEEE 40th International Conference on Electronics and Nanotechnology (ELNANO). IEEE, 2020. http://dx.doi.org/10.1109/elnano50318.2020.9088892.