17443677

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2

When examining HEK293 cells by whole-cell patch-clamp electrophysiology we found spontaneous currents, present in almost all cells. These currents were carried by Na(+) ions, were inhibited by amiloride and by cells exposure to acidic (pH 6.3) extracellular solutions. These properties (ion carrier, amiloride-sensitivity, and inactivation by constant lowering of extracellular pH) were similar to the properties of proton-activated currents measured from the same cells. Spontaneous currents required intracellular ATP, were completely inhibited by intracellular Ca(2+) buffering with BAPTA and were suppressed by intracellular administration of vesicular H(+)ATPase inhibitor bafilomycin. ATP-induced Ca(2+) influx through P2X receptors in HEK293 cells stably transfected with P2X(2), P2X(2/3) or P2X(4) purinoreceptor subunits transiently potentiated amplitude and frequency of spontaneous currents; this effect was antagonized by bafilomycin. We concluded that spontaneous currents represent activation of acid-sensitive ion channels (ASICs) by autocrine vesicular release of protons from HEK cells.

eng

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MEDLINE

0021-9541

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NLM

473-80

pubmed-meshheading:17443677-Adenosine Triphosphate, pubmed-meshheading:17443677-Amiloride, pubmed-meshheading:17443677-Autocrine Communication, pubmed-meshheading:17443677-Calcium, pubmed-meshheading:17443677-Cell Line, pubmed-meshheading:17443677-Chelating Agents, pubmed-meshheading:17443677-Dose-Response Relationship, Drug, pubmed-meshheading:17443677-Egtazic Acid, pubmed-meshheading:17443677-Enzyme Inhibitors, pubmed-meshheading:17443677-Exocytosis, pubmed-meshheading:17443677-Humans, pubmed-meshheading:17443677-Hydrogen-Ion Concentration, pubmed-meshheading:17443677-Membrane Potentials, pubmed-meshheading:17443677-Membrane Proteins, pubmed-meshheading:17443677-Nerve Tissue Proteins, pubmed-meshheading:17443677-Patch-Clamp Techniques, pubmed-meshheading:17443677-Proton-Translocating ATPases, pubmed-meshheading:17443677-Protons, pubmed-meshheading:17443677-Receptors, Purinergic P2, pubmed-meshheading:17443677-Receptors, Purinergic P2X2, pubmed-meshheading:17443677-Receptors, Purinergic P2X3, pubmed-meshheading:17443677-Receptors, Purinergic P2X4, pubmed-meshheading:17443677-Secretory Vesicles, pubmed-meshheading:17443677-Sodium, pubmed-meshheading:17443677-Sodium Channels, pubmed-meshheading:17443677-Transfection

Spontaneous autocrine release of protons activates ASIC-mediated currents in HEK293 cells.

Journal Article, Research Support, Non-U.S. Gov't