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Coupling of a P2Z‐like purinoceptor to a fatty acid‐activated K + channel in toad gastric smooth muscle cells
Author(s) -
Zou Hui,
Ugur Mehmet,
Drummond Robert M.,
Singer Joshua J.
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.00059.x
Subject(s) - biophysics , extracellular , membrane potential , egta , chemistry , ion channel , coupling (piping) , patch clamp , intracellular , receptor , biochemistry , biology , calcium , materials science , organic chemistry , metallurgy
1 Extracellular application of ATP generates two whole‐cell currents in toad gastric smooth muscle cells: an immediate inward non‐selective cation current (due to the activation of a P2X or P2Z‐like receptor) and a slowly developing outward K + current. The inward non‐selective cation current depends on the continuous presence of ATP while the outward K + current can last for minutes after ATP application ceases. 2 In cell‐attached patches, application of ATP to the extra‐patch membrane can activate K + channels in the patch indicating that a diffusible cellular messenger may be involved. The characteristics of these K + channels are similar to those of a previously described fatty acid‐activated K + channel that is also a stretch‐activated channel. 3 This whole‐cell K + current can be induced by ATP in the absence of extracellular Ca 2+ (with EGTA present to chelate trace amounts). However, the current generated in the presence of extracellular Ca 2+ is considerably larger. 4 The pharmacological profiles for the activation of the non‐selective cation current and the K + current are similar, suggesting that the same P2Z‐like receptor could be mediating both responses. This type of plasma membrane receptor/channel‐channel coupling by a process that does not appear to involve Ca 2+ flow through the receptor/channel or a subsequent membrane potential change may be representative of a new class of signalling mechanisms.