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Relevant bibliographies by topics / Oxygen channels

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Academic literature on the topic 'Oxygen channels'

Author: Grafiati

Published: 4 June 2021

Last updated: 2 February 2022

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Journal articles on the topic "Oxygen channels"

1

Kemp, Paul J., and Chris Peers. "Oxygen sensing by ion channels." Essays in Biochemistry 43 (August 10, 2007): 77–90. http://dx.doi.org/10.1042/bse0430077.

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The ability to sense and react to changes in environmental oxygen levels is crucial to the survival of all aerobic life forms. In mammals, specialized tissues have evolved which can sense and rapidly respond to an acute reduction in oxygen and central to this ability in many is dynamic modulation of ion channels by hypoxia. The most widely studied oxygen-sensitive ion channels are potassium channels but oxygen sensing by members of both the calcium and sodium channel families has also been demonstrated. This chapter will focus on mechanisms of physiological oxygen sensing by ion channels, with particular emphasis on potassium channel function, and will highlight some of the consensuses and controversies within the field. Where data are available, this chapter will also make use of information gleaned from heterologous expression of recombinant proteins in an attempt to consolidate what we know currently about the molecular mechanisms of acute oxygen sensing by ion channels.

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Prentice, Howard M., Sarah L. Milton, Daniela Scheurle, and Peter L. Lutz. "Gene transcription of brain voltage-gated potassium channels is reversibly regulated by oxygen supply." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 285, no. 6 (December 2003): R1317—R1321. http://dx.doi.org/10.1152/ajpregu.00261.2003.

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Voltage-dependent potassium channels (Kv channels) are important determinants of brain electrical activity. Hypoxia may be an important modifier, because several voltage-gated K+ channels are reversibly blocked by acute hypoxia and are thought to act as oxygen sensors. Here we show, using the anoxia-tolerant turtle brain ( Trachemys scripta) as a model, that brain Kv1 channel transcription is reversibly regulated by oxygen supply. We found that in turtle brains exposed to 4-h anoxia Kv1 transcripts were reduced to 18.5% of normoxic levels. Kv1 channel mRNA levels were restored to normal within 4 h of subsequent reoxygenation. Our results provide clear evidence that brain Kv channel expression is sensitive to oxygen supply and indicate an important mechanism that matches brain activity to oxygen supply.

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Peers, C. "Oxygen-sensitive ion channels." Trends in Pharmacological Sciences 18, no. 11 (November 1, 1997): 405–8. http://dx.doi.org/10.1016/s0165-6147(97)01120-6.

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Peers, Chris. "Oxygen-sensitive ion channels." Trends in Pharmacological Sciences 18, no. 4 (July 1997): 405–8. http://dx.doi.org/10.1016/s0165-6147(97)90669-6.

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Ganfornina, M. D., and J. López-Barneo. "Potassium channel types in arterial chemoreceptor cells and their selective modulation by oxygen." Journal of General Physiology 100, no. 3 (September 1, 1992): 401–26. http://dx.doi.org/10.1085/jgp.100.3.401.

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Single K+ channel currents were recorded in excised membrane patches from dispersed chemoreceptor cells of the rabbit carotid body under conditions that abolish current flow through Na+ and Ca2+ channels. We have found three classes of voltage-gated K+ channels that differ in their single-channel conductance (gamma), dependence on internal Ca2+ (Ca2+i), and sensitivity to changes in O2 tension (PO2). Ca(2+)-activated K+ channels (KCa channels) with gamma approximately 210 pS in symmetrical K+ solutions were observed when [Ca2+]i was greater than 0.1 microM. Small conductance channels with gamma = 16 pS were not affected by [Ca2+]i and they exhibited slow activation and inactivation time courses. In these two channel types open probability (P(open)) was unaffected when exposed to normoxic (PO2 = 140 mmHg) or hypoxic (PO2 approximately 5-10 mmHg) external solutions. A third channel type (referred to as KO2 channel), having an intermediate gamma(approximately 40 pS), was the most frequently recorded. KO2 channels are steeply voltage dependent and not affected by [Ca2+]i, they inactivate almost completely in less than 500 ms, and their P(open) reversibly decreases upon exposure to low PO2. The effect of low PO2 is voltage dependent, being more pronounced at moderately depolarized voltages. At 0 mV, for example, P(open) diminishes to approximately 40% of the control value. The time course of ensemble current averages of KO2 channels is remarkably similar to that of the O2-sensitive K+ current. In addition, ensemble average and macroscopic K+ currents are affected similarly by low PO2. These observations strongly suggest that KO2 channels are the main contributors to the macroscopic K+ current of glomus cells. The reversible inhibition of KO2 channel activity by low PO2 does not desensitize and is not related to the presence of F-, ATP, and GTP-gamma-S at the internal face of the membrane. These results indicate that KO2 channels confer upon glomus cells their unique chemoreceptor properties and that the O2-K+ channel interaction occurs either directly or through an O2 sensor intrinsic to the plasma membrane closely associated with the channel molecule.

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Chung, Chin Ming, Ching Huei Lin, and Che Wei Lin. "COMSOL Simulations for Flow Channels of Low-Temperature Fuel Cell." Advanced Materials Research 343-344 (September 2011): 261–66. http://dx.doi.org/10.4028/www.scientific.net/amr.343-344.261.

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A multiple physical finite elements to analyze software (COMSOL Multiphysics) is employed to investigate serpentine flow channels of a small proton exchange membrane fuel cell with power 0.5W. Distributions of the oxygen flow, the liquid water, and the electric current density in three different designed flow channels are simulated and compared. Results show that increasing the channel width is conducive to increase the oxygen flow and reduce the production of liquid water. It thus enhances the electric current density. However, it will reduce the oxygen flow, produce more liquid water, and depress the current density if the channel width is decreased.

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Soto, Marco A., Carlos González, Eduardo Lissi, Cecilia Vergara, and Ramón Latorre. "Ca2+-activated K+ channel inhibition by reactive oxygen species." American Journal of Physiology-Cell Physiology 282, no. 3 (March 1, 2002): C461—C471. http://dx.doi.org/10.1152/ajpcell.00167.2001.

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We studied the effect of H2O2 on the gating behavior of large-conductance Ca2+-sensitive voltage-dependent K+ (KV,Ca) channels. We recorded potassium currents from single skeletal muscle channels incorporated into bilayers or using macropatches of Xenopus laevisoocytes membranes expressing the human Slowpoke(h Slo) α-subunit. Exposure of the intracellular side of KV,Ca channels to H2O2 (4–23 mM) leads to a time-dependent decrease of the open probability ( P o) without affecting the unitary conductance. H2O2 did not affect channel activity when added to the extracellular side. These results provide evidence for an intracellular site(s) of H2O2 action. Desferrioxamine (60 μM) and cysteine (1 mM) completely inhibited the effect of H2O2, indicating that the decrease in P o was mediated by hydroxyl radicals. The reducing agent dithiothreitol (DTT) could not fully reverse the effect of H2O2. However, DTT did completely reverse the decrease in P o induced by the oxidizing agent 5,5′-dithio-bis-(2-nitrobenzoic acid). The incomplete recovery of KV,Ca channel activity promoted by DTT suggests that H2O2 treatment must be modifying other amino acid residues, e.g., as methionine or tryptophan, besides cysteine. Noise analysis of macroscopic currents in Xenopus oocytes expressing h Slo channels showed that H2O2 induced a decrease in current mediated by a decrease both in the number of active channels and P o.

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Kim, Donghee. "Oxygen sensing with ion channels." Channels 8, no. 4 (July 2014): 290–91. http://dx.doi.org/10.4161/chan.29966.

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López-Barneo, Jóse, Patricia Ortega-Sáenz, Antonio Molina, Alfredo Franco-Obregón, Juan Ureña, and Antonio Castellano. "Oxygen sensing by ion channels." Kidney International 51, no. 2 (February 1997): 454–61. http://dx.doi.org/10.1038/ki.1997.61.

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Ivanov, I. I., A. V. Loktyushkin, R. A. Gus’kova, N. S. Vasil’ev, G. E. Fedorov, and A. B. Rubin. "Oxygen channels of erythrocyte membrane." Doklady Biochemistry and Biophysics 414, no. 1 (June 2007): 137–40. http://dx.doi.org/10.1134/s160767290703012x.

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Dissertations / Theses on the topic "Oxygen channels"

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Takahashi, Nobuaki. "TRP channels as sensors of cellular redox status." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/131892.

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Giacomin, Paul R. "Understanding the mechanism of oxygen sensitivity of SK channels /." Title page and summary only, 2002. http://web4.library.adelaide.edu.au/theses/09SB/09SBg429.pdf.

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Saam, Jan. "Identification of dynamic oxygen access channels in 12/15-lipoxygenase." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15744.

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Zellen enthalten zahlreiche Enzyme, deren Reaktionen von molekularem Sauerstoff abhängen. Oft sind deren aktive Zentren tief im inneren des Proteins verborgen, was die Frage nach spezifischen Zugangskanälen, die den Sauerstoff gezielt zum Ort der Katalyse leiten, aufwirft. In der vorliegenden Arbeit wird dies am Beispiel der 12/15-Lipoxygenase, als ein typisches Beipiel Sauerstoff verbrauchender Enzyme, untersucht. Die Sauerstoffverteilung innerhalb des Proteins wurde bestimmt und mögliche Routen für den Sauerstoffzugang definiert. Zu diesem Zweck wurden theoretische Untersuchungen eng mit Experimenten verzahnt. Zuerst wurden Molekulardynamik Simulationen des Proteins in Lösung durchgeführt. Aus den Trajektorien konnte die dreidimensionale Verteilung der Freien Enthalpie für Sauerstoff berechnet werden. Die Analyse der günstigsten Pfade in dieser Energielandschaft führte zur Identifikation von vier Sauerstoffkanälen im Protein. Alle Kanäle verbinden die Proteinoberfläche mit einem Gebiet hoher Sauerstoffaffinität am aktiven Zentrum. Diese Region liegt bezüglich des Substrats gegenüber dem Eisenzentrum, wodurch eine strukturelle Erklärung für die Reaktionsspezifität des Enzyms gegeben ist. Der katalytisch bedeutsamste Weg des Sauerstoffs kann durch L367F Austauschmutation blockiert werden, was zu einer stark erhöhten Michaelis-Konstante für Sauerstoff führt. Diese experimentell nachgewiesene Blockade konnte, mit Hilfe entsprechender Molekulardynamik Simulationen, durch eine Umordnung eines Wasserstoffbrücken-Netzwerks von Wassermolekülen innerhalb des Protein im Detail erklärt werden. Die Ergebnisse ermöglichen den Schluss, dass die Hauptroute für Sauerstoff zum aktiven Zentrum des Enzyms einem Kanal folgt, der aus vorübergehend verbundenen Hohlräumen besteht. Hierbei unterliegt das Öffnen und Schließen des Kanals der Dynamik der Proteinseitenketten.
Cells contain numerous enzymes utilizing molecular oxygen for their reactions. Often, their active sites are buried deeply inside the protein which raises the question whether there are specific access channels guiding oxygen to the site of catalysis. In the present thesis this question is investigated choosing 12/15-lipoxygenase as a typical example for such oxygen dependent enzymes. The oxygen distribution within the protein was determined and potential routes for oxygen access were defined. For this purpose an integrated strategy of structural modeling, molecular dynamics simulations, site directed mutagenesis, and kinetic measurements has been applied. First, molecular dynamics simulations of the protein in solution were performed. From the trajectories, the 3-dimensional free-energy distribution for oxygen could be computed. Analyzing energetically favorable paths in the free-energy map led to identification of four oxygen channels in the protein. All channels connect the protein surface with a zone of high oxygen affinity at the active site. This region is localized opposite to the non-heme iron providing a structural explanation for the reaction specificity of this lipoxygenase isoform. The catalytically most relevant path can be obstructed by L367F exchange which leads to a strongly increased Michaelis constant for oxygen. This experimetally proven blocking mechanism can, by virtue of molecular dynamics studies, be explained in detail through a reordering of the hydrogen bonding network of water molecules. As a conclusion, the results provide strong evidence that the main route for oxygen access to the active site of the enzyme follows a channel formed by transiently interconnected cavities whereby the opening and closure is governed by sidechain dynamics.

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Wang, Jie. "Mechanisms of oxygen sensing by KV3.1b channels expressed in HEK293 cells." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401507.

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Idikuda, Vinaykumar. "REGULATION OF HCN CHANNEL FUNCTION BY DIRECT cAMP BINDING AND SINGLET OXYGEN." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5455.

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Hyperpolarization-activated, cyclic-nucleotide gated ion channels (HCN channels) are activated by membrane hyperpolarization and modulated by cyclic nucleotides. HCN channels are important to maintain the resting membrane potential and input resistance in neurons and have important physiological functions in the brain and heart. Four mammalian HCN isoforms, HCN1-4, and the isoform cloned from sea urchin, spHCN, have been extensively studied. Among these, only spHCN channel shows a voltage dependent inactivation. Previous studies have shown that the ligand binding in mHCN2 channel is activity dependent: cAMP binding increases along with channel opening or channels in the open state have higher binding affinity for cAMP. But to date, information pertaining to the ligand binding to an inactivated ion channel or desensitized receptor is lacking. To address this gap, we used fluorescently labelled cAMP analogues in conjunction with patch clamp fluorometry (PCF) to study the ligand binding to the spHCN channel in various conformational states. We show that inactivated spHCN channel shows reduced binding affinity for cAMP, compared to that of the closed or open channel. Parallelly, we noticed significant changes to channel function when a combination of laser and photosensitizer was used to study ligand binding. A reactive oxygen species called singlet oxygen has been confirmed to be the major player in this process. Both photo-dynamically generated and chemically generated singlet oxygen modifies spHCN channel by removing the inactivation. The effect of singlet oxygen on channel can be abolished by the mutation of a key histidine (H462) residue in the ion conducting pore. Taken together, these two projects expanded our understanding about the physicochemical nature of fluorophores from two aspects: (i) the release of photon as a valuable tool to study the conformational dynamics in proteins; (ii) the generation of singlet oxygen as an effective modulator of protein function.

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Ogawa, Nozomi. "Detection of cellular redox status by transient receptor potential channels." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215577.

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Holdsworth, Clark Thomas. "Vascular ATP-sensitive potassium channels impact spatial and temporal oxygen transport: implications for sulphonylurea therapy." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/20562.

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Doctor of Philosophy
Department of Anatomy and Physiology
Timothy I. Musch
Matching local muscle O[subscript]2-supply to O[subscript]2-demand during the prodigious exercise-induced metabolic challenge is achieved through coordinated mechanisms of vascular control. The unique sensitivity of ATP-sensitive potassium (K[subscript]ATP) channels to cell metabolism indicates the potential to match energetic demand to peripheral O[subscript]2 transport. The aim of this dissertation was to determine the magnitude and kinetics of the K[subscript]ATP channel contribution to vascular control during exercise in health and heart failure. It was hypothesized that K[subscript]ATP channel inhibition via glibenclamide would, in healthy rats, 1) reduce exercising skeletal muscle blood flow and vascular conductance 2) speed the fall of microvascular O[subscript]2 driving pressure (PO[subscript]2mv; set by the O[subscript]2 delivery-O[subscript]2 utilization ratio) during muscle contractions and 3) in heart failure rats, augment the PO[subscript]2mv undershoot and delay the time to reach the contracting steady-state. A total of 55 male Sprague-Dawley rats were used under control and glibenclamide conditions (5 mg kg[superscript]-1). Hindlimb muscle blood flow (radiolabelled microspheres) was determined at rest (n = 6) or during treadmill exercise (n = 6-8; 20, 40 and 60 m min[superscript]-1, 5% incline). Spinotrapezius muscle PO[subscript]2mv (phosphorescence quenching) was measured in 16 heart failure (coronary artery ligation) and 12 healthy rats and during 180 s of 1-Hz twitch contractions (~6 V). The major effects of glibenclamide were, in healthy rats, 1) a reduction in exercising hindlimb skeletal muscle blood flow with the greatest effect in predominantly oxidative muscle fiber types and at higher running speeds 2) an increased prevalence of the undershoot of PO[subscript]2mv steady-state and doubled time to reach the steady-state and 3) in heart failure rats, a reduced baseline PO[subscript]2mv, an augmented undershoot of the steady-state and time to reach steady-state and a reduction in the mean PO[subscript]2mv during contractions. These data suggest that the K[subscript]ATP channel contributes substantially to exercise-induced hyperemia and may contribute to the slowing of VO[subscript]2 kinetics given the spatial and temporal effects of glibenclamide. The K[subscript]ATP channel-mediated protection against a severe O[subscript]2-delivery to O[subscript]2-utilization mismatch at the onset of contractions raises serious concerns for sulphonylurea treatment in diabetes which is likely to cause perturbations of [metabolite] and compromise exercise tolerance.

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Yamamoto, Shinichiro. "Reactive Oxygen Species / Reactive Nitrogen Species-sensitive TRP channels : Molecular Activation Mechanism and Physiological Significance." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/124503.

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Oliveira, Vanda Cristina Paiva Tavares de. "Cork structural characteristics and their influence on the oxygen ingress through wine stoppers." Doctoral thesis, ISA-UL, 2016. http://hdl.handle.net/10400.5/12037.

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Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia - UL
Cork structural characteristics and their influence on the oxygen ingress through wine stoppers were studied aiming to contribute to an increased added-value of the natural cork stoppers. The surface porosity features of cork stoppers can differentiate the three main commercial classes used nowadays: the porosity coefficient was 2.4%, 4.0% and 5.5% for premium, good and standard stoppers, respectively. Image analysis also distinguished defects in the cork structure: empty ant gallery; Coroebus undatus F. larvae gallery; and wetcork. Several predictive classification models of stoppers into quality classes were built using the results from cork stoppers surface characterization and a simplified model using the main discriminant features i.e. porosity coefficient and the RGB colour-type variables was presented. X-ray tomography was used as a non-destructive technique to study the internal structure of natural cork stoppers, allowing the visualization of some defects inside the cork stopper. After characterization, the natural cork stoppers were used as closure of bottles and oxygen diffusion measurements were made along time. The kinetics of oxygen transfer was similar and could be adjusted to logarithmic models. On average 35% of the overall oxygen ingress occurred in the first 5 days, 59% in the 1st month and 78% in the first 3 months. Microtomography images (voxel size of 50 µm) allowed the observation of lenticular channels development and geometry, and the quantification of void and high density regions (HDR) fractions. The evidence that the void fraction of lenticular channels in the innermost part of the cork stopper inserted in the bottle was strongly related to the oxygen ingress in the first month after bottling can be used for quality enhancement of natural cork stoppers with incorporation of performance requirements

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Garlid, Anders Olav. "Mitochondrial Reactive Oxygen Species (ROS): Which ROS is Responsible for Cardioprotective Signaling?" PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1641.

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Mitochondria are the major effectors of cardioprotection by procedures that open the mitochondrial ATP-sensitive potassium channel (mitoKATP), including ischemic and pharmacological preconditioning. MitoKATP opening leads to increased reactive oxygen species (ROS), which then activate a mitoKATP-associated PKCε, which phosphorylates mitoKATP and leaves it in a persistent open state (Costa, ADT and Garlid, KD. Am J Physiol 295, H874-82, 2008). Superoxide (O2•-), hydrogen peroxide (H2O2), and hydroxyl radical (HO•) have each been proposed as the signaling ROS but the identity of the ROS responsible for this feedback effect is not known. Superoxide was excluded in earlier work on the basis that it does not activate PKCε and does not induce mitoKATP opening.To further examine the identity of the signaling ROS, respiring rat heart mitochondria were preincubated with ATP and diazoxide to induce the phosphorylation-dependent open state, together with agents that may interrupt feedback activation of mitoKATP by ROS scavenging or by blocking ROS transformations. Swelling assays of the preincubated mitochondria revealed that dimethylsulfoxide (DMSO), dimethylformamide (DMF), deferoxamine, trolox, and bromoenol lactone (BEL) each blocked the ROS-dependent open state but catalase did not interfere with this step. The lack of a catalase effect and the inhibitory effects of agents acting downstream of HO• excludes H2O2 as the endogenous signaling ROS and focuses attention on HO•. In support of the hypothesis that HO• is required, we also found that HO•-scavenging by DMF blocked cardioprotection by both ischemic preconditioning and diazoxide in the Langendorff perfused rat heart. HO• itself cannot act as a signaling molecule, because its lifetime is too short and it reacts immediately with nearest neighbor phospholipids and proteins. Therefore, these findings point to a product of phospholipid peroxidation, such as hydroperoxy-fatty acids. Indeed, this hypothesis was supported by the finding that hydroperoxylinoleic acid (LAOOH) opens the ATP-inhibited mitoKATP in isolated mitochondria. This effect was blocked by the specific PKCε inhibitor peptide εV1-2, showing that LAOOH activates the mitoKATP-associated PKCε. During ischemia, catabolism of mitochondrial phospholipids is accelerated, causing accumulation of plasmalogens and free fatty acids (FA) in the heart by the action of calcium independent phospholipases A2 (iPLA2). We first assessed the role of FAs and hydroxy FAs on mitoKATP opening and cardioprotection. Swelling assays of isolated rat heart mitochondria showed that naturally formed free FAs inhibit mitoKATP opening and that they are more potent inhibitors of the pharmacological open state of mitoKATP than the phosphorylation-dependent open state. That is, sustained mitoKATP opening induced by the phosphorylation-dependent feedback loop is more resistant to FA inhibition than direct mitoKATP opening by a potassium channel opener. Moreover, rat hearts perfused with micromolar concentrations of FA were resistant to cardioprotection by diazoxide or ischemic preconditioning. Racemic bromoenol lactone (BEL), a selective inhibitor of iPLA2, confers protection to otherwise untreated Langendorff perfused hearts by preventing ischemic FA release. To bring this story full circle, BEL blocks protection afforded by preconditioning and postconditioning by preventing the iPLA2-mediated release of FAOOH generated in the conditioned heart. HO• resulting from mitoKATP opening oxidizes polyunsaturated fatty acid components of the membrane phospholipids, resulting in a peroxidized side chain. FAOOH must be released in order to act on the mitochondrial PKCε, and this is achieved by the action of iPLA2. iPLA2 is essential for most modes of cardioprotection because it catalyzes the release of FAOOH. This fully supports the hypothesis that the second messenger of cardioprotective ROS-mediated signaling is hydroperoxy fatty acid (FAOOH), a downstream oxidation product of HO•.

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Books on the topic "Oxygen channels"

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D, Lambris John, Peers Chris, Cohen Irun R, Nurse Colin A, Gonzalez Constancio, Paoletti Rodolfo, Lajtha Abel, and SpringerLink (Online service), eds. Arterial Chemoreceptors: Arterial Chemoreceptors. Dordrecht: Springer Netherlands, 2009.

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J, López-Barneo, and Weir E. Kenneth, eds. Oxygen regulation of ion channels and gene expression. Armonk, N.Y: Futura Pub., 1998.

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Douglas, Kenneth. Bioprinting. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780190943547.001.0001.

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Abstract: This book describes how bioprinting emerged from 3D printing and details the accomplishments and challenges in bioprinting tissues of cartilage, skin, bone, muscle, neuromuscular junctions, liver, heart, lung, and kidney. It explains how scientists are attempting to provide these bioprinted tissues with a blood supply and the ability to carry nerve signals so that the tissues might be used for transplantation into persons with diseased or damaged organs. The book presents all the common terms in the bioprinting field and clarifies their meaning using plain language. Readers will learn about bioink—a bioprinting material containing living cells and supportive biomaterials. In addition, readers will become at ease with concepts such as fugitive inks (sacrificial inks used to make channels for blood flow), extracellular matrices (the biological environment surrounding cells), decellularization (the process of isolating cells from their native environment), hydrogels (water-based substances that can substitute for the extracellular matrix), rheology (the flow properties of a bioink), and bioreactors (containers to provide the environment cells need to thrive and multiply). Further vocabulary that will become familiar includes diffusion (passive movement of oxygen and nutrients from regions of high concentration to regions of low concentration), stem cells (cells with the potential to develop into different bodily cell types), progenitor cells (early descendants of stem cells), gene expression (the process by which proteins develop from instructions in our DNA), and growth factors (substances—often proteins—that stimulate cell growth, proliferation, and differentiation). The book contains an extensive glossary for quick reference.

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E, Vance Dennis, and Vance Jean E, eds. Biochemistry of lipids, lipoproteins, and membranes. Amsterdam: Elsevier, 1991.

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Book chapters on the topic "Oxygen channels"

1

Conforti, Laura, and David E. Millhorn. "Regulation of Shaker-Type Potassium Channels by Hypoxia." In Oxygen Sensing, 265–74. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-46825-5_25.

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Haddad, Gabriel G., and Huajun Liu. "Different O2-Sensing Mechanisms by Different K+ Channels." In Oxygen Sensing, 441–52. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-46825-5_43.

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A, S. L., E. K. W, H. L. R, and E. M. "Molecular Identification of O2 Sensors and O2-Sensitive Potassium Channels in the Pulmonary Circulation." In Oxygen Sensing, 219–40. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-46825-5_21.

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Delpiano, Marco A. "ATP-Dependent K+ and Voltage-Gated Ca2+ Channels in Endothelial Cells of Brain Capillaries." In Oxygen Sensing, 435–40. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/0-306-46825-5_42.

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Pasquali, F., G. Menestrina, and R. Antolini. "Electrical Properties of Ionic Channels Formed by Helix Pomatia Hemocyanin in Planar Lipid Bilayers." In Invertebrate Oxygen Carriers, 361–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-71481-8_60.

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Demidchik, Vadim. "Reactive Oxygen Species, Oxidative Stress and Plant Ion Channels." In Ion Channels and Plant Stress Responses, 207–32. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10494-7_11.

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Reeve, Helen L., Martin Tristani-Firouzi, Simona Tolarova, Stephen L. Archer, and E. Kenneth Weir. "K+ Channels and the Normoxic Constriction of the Rabbit Ductus Arteriosus." In Oxygen Homeostasis and Its Dynamics, 473–78. Tokyo: Springer Japan, 1998. http://dx.doi.org/10.1007/978-4-431-68476-3_60.

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Murray, James, and James Barber. "Oxygen, Water, Proton and Quinone Channels in PSII." In Photosynthesis. Energy from the Sun, 467–70. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6709-9_105.

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Kemp, Paul J., Sandile E. J. Williams, Helen S. Mason, Phillippa Wootton, David E. Iles, Daniela Riccardi, and Chris Peers. "Functional Proteomics of BK Potassium Channels: Defining the Acute Oxygen Sensor." In Signalling Pathways in Acute Oxygen Sensing, 141–56. Chichester, UK: John Wiley & Sons, Ltd, 2008. http://dx.doi.org/10.1002/9780470035009.ch12.

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Harrison, D. K., S. Birkenhake, S. Knauf, N. Hagen, I. Beier, and M. Kessler. "The Role of High Flow Capillary Channels in the Local Oxygen Supply to Skeletal Muscle." In Oxygen Transport to Tissue X, 623–30. New York, NY: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4615-9510-6_77.

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Conference papers on the topic "Oxygen channels"

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Melnikov, Igor, Nikita Muravyev, Ilya Kuchurov, Alla Pivkina, and Vitaly Kiselev. "KINETICS AND MECHANISM PRIMARY DECOMPOSITION CHANNELS OF BCHMX FROM HIGH ACCURACY QUANTUM CHEMISTRY CALCULATIONS." In Chemistry of nitro compounds and related nitrogen-oxygen systems. LLC MAKS Press, 2019. http://dx.doi.org/10.29003/m770.aks-2019/275-278.

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Fujii, Yoshinobu, Shohji Tsushima, and Shuichiro Hirai. "Optical Remote Sensing of Oxygen and Water Vapor Concentration in PEMFC Channel by Using Tunable Diode Laser Absorption Spectroscopy Techniques." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32728.

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In this study, we present optical remote sensing of oxygen and water vapor concentration in gas flow channels in an operating polymer electrolyte membrane fuel cell (PEMFC) by using Tunable Diode Laser Absorption Spectroscopy (TDLAS). Wavelengths of the diode laser are 1392nm for measurement of water vapor concentration and 760nm for measurement of oxygen concentration, respectively. We demonstrated that the optical remote sensing based on TDLAS techniques could detect variation of oxygen and water vapor concentration in the PEMFC channel.

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Kim, Han-Sang, Taehun Ha, and Kyoungdoug Min. "A Study of Water and Oxygen Distributions in the Cathode Flow Channels of a PEM Fuel Cell." In ASME 2006 4th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2006. http://dx.doi.org/10.1115/fuelcell2006-97240.

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Water management is a critical operation issue for achieving the highest possible performance of proton exchange membrane (PEM) fuel cells. Quantitative determination of water and species distribution is needed to understand the water management and reactant distribution effects. In this study, the measurement of water and oxygen distributions along cathode flow channels was carried out using gas chromatography (GC). Generally, it is difficult to measure water distribution where water concentration is too high. Here, the measurement of high levels of water saturation in cathode channels was performed according to fuel cell operating conditions. GC measurement was also carried out for flooding and non-flooding conditions. To compare the experimental results with computational results, the three-dimensional CFD simulation of a unit fuel cell was performed using es-pemfc, which is the PEM fuel cell module of commercial CFD code STAR-CD. For the entrance of flow channel that has relatively lower level of water content, the calculated results showed good agreement with measured results. However, some discrepancy between calculated and experimental results was still found for the flow channels near the cathode outlet. The study provides the necessity of the development and adoption of a comprehensive multidimensional PEM fuel cell models including two-phase flow and cathode flooding phenomena for the optimization of fuel cell performance.

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Gerard, Mathias, Jean-Philippe Poirot-Crouvezier, Daniel Hissel, and Marie-Cecile Pe´ra. "Oxygen Starvation Effects on PEMFC Durability." In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33173.

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The problem of oxygen starvation on PEMFC is often observed (partially or totally in a cell). It is caused by water management problems (water droplet in the channels) or air management faults (delay during peak power). In our previous work, the current distribution has been measured along the cell during air starvation and calculated by modeling; the effects of the local temperature and the hygrometry in the MEA have been identified. However the mechanisms of degradation are still not completely understood. Several points have to be investigated like the short and long dated changes in performances and the degradation mechanisms in such a condition. In this paper, the study is completed by two sets of experiments. The first one is carried out with a bi-cell stack developed with specific design to compute the local current density by measuring the local induced magnetic field. Secondly, a long time ageing test is run with a 6 cells stack (220 cm2) during oxygen starvation cycling conditions. Both tests (with characterizations) coupled with the 2D serpentine meshing stack model (taking into account transport phenomena, heat transfer and semi-empirical electrochemical reactions) provide information on the MEA local conditions effects during oxygen starvation. Especially the different reaction mechanisms at the cathode side are explained likewise the consequences on ageing.

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Inagaki, Suguru, Hiroki Nagai, and Keisuke Asai. "Measurement of Oxygen Partial Pressure Distribution in a Fuel Cell Using Pressure-Sensitive Paint." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32751.

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To improve efficiency and service life of a fuel cell, it is important to understand the dynamic behavior of oxygen molecules in the cell. In other words, we need to know the oxygen concentration distribution over electrode planes and inside diffused layers in addition to its time variation. We applied the Pressure-Sensitive Paint (PSP) technique to this problem, attempting to measure distribution of partial pressure oxygen along micro channels of a fuel cell. To prevent the effect of water produced by the power generation process, we developed a water-repellent PSP that can withstand heat and humidity produced by power generation. Using this paint, partial oxygen distribution along the micro channels was successfully visualized, although there were noticeable effects of local temperature distribution on the absolute accuracy for the conditions with higher current densities.

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Tabuchi, Yuichiro, and Norio Kubo. "The Impact of Rib/Channel, Water and Heat Transport on Limiting Current Density." In ASME 2008 6th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/fuelcell2008-65201.

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Proton exchange membrane fuel cells (PEMFCs) are regarded as a promising alternative clean power source for automotive applications. Key to the acceptance of PEMFCs for automobiles are cost reduction and power density for compactness. In order to meet these requirements, further improvement of cell performance is required. In particular, under higher current density operation, water and heat transport in PEMFC have strong effects on cell performance. In this study, the impact of Rib/Channel dimensions, heat and water transport on cell performance under high current density is investigated using the multiphase mixture model (M2 model), and the limiting current density is evaluated using a uniform test cell with 10cm2 active area and 24 straight channels. Limiting current densities were measured under different oxygen concentrations at 70°C and 70% relative humidity at both sides. In order to neglect the effect of liquid water in channels and the distribution of oxygen and hydrogen concentrations along the flow channel, large flow rates were introduced at both sides. Experimental results show a nonlinear relation between oxygen concentration in the channel and limiting current density. Numerically it is found that this nonlinear trend is caused by liquid water in the Rib region. In addition, it is also found that not only liquid water, but also heat transport and water transport through the membrane significantly affect the limiting current density. Finally, it is concluded that the combination analysis using limiting current experiments of uniform cell system and M2 model is very useful for fundamental understanding and for fuel cell design optimization.

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Taira, Hidetaka, and Hongtan Liu. "Numerical Analysis of the Cross-Flow Under the Land in a Serpentine Flow Field of a PEM Fuel Cell." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64031.

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Serpentine flow-fields are widely used in proton exchange membrane (PEM) fuel cells due to their various advantages, including providing a proper compromise between pressure drop and water removal capability. One of the advantages of serpentine flow fields is the cross-flow under the land through the gas diffusion layer (GDL) due to the pressure difference between adjacent channels. In this study, a three-dimensional PEM fuel cell model is developed to study the cross-flow effect under the land for both across and along the land directions. Simulation results of the flow distribution along and across the channel, and the relationship between the cross-flow and the pressure difference are presented. A parametric study is conducted to investigate the effect of the GDL permeability on the cross-flow rate. The cross-flow rate increases as the permeability becomes larger because the cross-flow velocity. However, cross-flow rate reaches an asymptotic value when the permeability is greater than 10−9 (m2) since the pressure difference between adjacent channels becomes smaller. The effect of the cross-flow on the local oxygen mass fraction is also investigated. The results show that oxygen concentrations in some locations are significantly higher due to the cross-flow under the land and secondary flows in the channel. Finally, by comparing average current densities between under the channels and the land areas, it is shown that the performance of the cell gradually decreases across the channel/land direction.

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Karthikeyan, P., H. Calvin Li, G. Lipscomb, S. Neelakrishnan, J. G. Abby, and R. Anand. "Experimental Investigation of the Water Impact on Performance of Proton Exchange Membrane Fuel Cells (PEMFC) With Porous and Non-Porous Flow Channels." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-85865.

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The most critical aspect of fuel cell water management is the delicate balance of membrane hydration and avoiding cathode flooding. Liquid water accumulation in the interfacial contact area between the flow channel landing and gas diffusion layer (GDL) can dramatically impact steady and transient performance of proton exchange membrane fuel cells (PEMFCs). In this concern, a porous landing could facilitate water removal in the cathode flow channel and significantly improve PEMFCs performance. In this work, an attempt has been made to fabricate the porous interdigitated cathode flow channels from a porous carbon sheet. Performance measurements have been made with nominally identical PEMFCs using non-porous (serpentine and interdigitated) and porous (interdigitated) cathode flow channels. PEMFCs with porous interdigitated flow channels had 48% greater power output than PEMFCs with non-porous interdigitated flow channels at high current densities. For the non-porous interdigitated flow channel, significant performance loss appears to arise from greatly reduced oxygen transport rates when the water generation rate exceeds the water removal rate, however for the porous interdigitated flow channel, the design removes the accumulated liquid water from the landing area through the capillarity of its porous structure and eliminates the stagnant regions under the landing, thereby reducing liquid flooding in the interface between landing and GDL area.

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9

Siefert, Nicholas, Colin O’Shea, and Shawn Litster. "The Role of Channel Plurality in Two-Phase Flow Instabilities in PEM Cathode Channels." In ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology collocated with ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/fuelcell2011-54408.

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Water management is a critical issue in the development of proton exchange membrane (PEM) fuel cells with robust operation. Liquid water can accumulate and flood the gas delivery microchannels and the porous electrodes within PEM fuel cells and deteriorate performance. Since the liquid distribution fluctuates in time for two-phase flow, the rate of oxygen transport to the cathode catalyst layer also fluctuates, resulting in unstable power density and efficiency. In previous research into measuring the voltage loss and voltage fluctuation due to two-phase flow instabilities in the cathode channels of PEM fuel cells, we investigated the effect of the number of parallel channels covering the active area by studying flow fields with varying numbers of parallel channels (4 to 25) while keeping the active area constant at 5 cm2. The resulting voltage loss and fluctuation measurements were expressed as functions of two non-dimensional parameters: channel plurality and the air flow stoichiometric ratio. Channel plurality is a flow field design parameter that defines the number of channels per unit of active area, which is non-dimensionalized by the cross-sectional area of the channels. In this paper, we expand upon our prior studies by studying cathode flow field designs of varying active area, from 5 cm2 to 25 cm2, with a constant number of 25 channels. By increasing the active area with a constant number of channels, we are reducing the channel plurality value. The new results are mapped back to the non-dimensional parameters to extract empirical scaling rules for voltage loss and fluctuation. Furthermore, we compare this data to our prior work with constant active area and identify the significance of the fuel cell size in the scaling relationships. Finally, a refined scaling is presented for generalizing the results for fuel cells having different active area and number of channels.

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Wetton, Brian, Gwang-Soo Kim, Keith Promislow, Jean St-Pierre, and John Stockie. "Universal Mass-Transport Limited Fuel Cell Current Curves." In ASME 2005 3rd International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2005. http://dx.doi.org/10.1115/fuelcell2005-74093.

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A unit fuel cell with straight gas channels operating in low voltage conditions is considered. Anode electrochemical losses are neglected and a particular, simple form for mass transport limitations to the cathode oxygen reduction electrochemistry is taken and validated with experimental results. With experimentally fitted parameters, it is found that the mass transport limitations dominate the behaviour of the local current density at low voltages. Combined with a simple channel model for oxygen flux, this leads to a description of local current densities independent of cell voltage, assuming only that it is low. The work is motivated by Polymer Electrolyte Membrane fuel cells but the ideas are general enough to be applied to other fuel cell types.

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