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Spontaneous autocrine release of protons activates ASIC‐mediated currents in HEK293 cells
Author(s) -
Lalo Ulyana,
Pankratov Yuri,
North R. Alan,
Verkhratsky Alexei
Publication year - 2007
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.21043
Subject(s) - autocrine signalling , hek 293 cells , microbiology and biotechnology , chemistry , biophysics , cell culture , biology , genetics
Abstract 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. © 2007 Wiley‐Liss, Inc. J. Cell. Physiol. 212: 473–480, 2007. © 2007 Wiley‐Liss, Inc.