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Extracellular Ca 2+ ‐activated K channel in coronary artery smooth muscle cells and its role in vasodilation
Author(s) -
Inoue Isao,
Nakaya Yutaka,
Nakaya Shuichiro,
Mori Hiroyoshi
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81106-8
Subject(s) - nicorandil , charybdotoxin , extracellular , chemistry , vasodilation , channel blocker , repolarization , tetraethylammonium , biophysics , myocyte , medicine , membrane potential , electrophysiology , calcium , biochemistry , biology , potassium , organic chemistry
An extracellular Ca 2+ ‐activated K channel (K R channel), having a conductance of 30 pS, was identified in isolated single smooth muscle cells from porcine coronary artery. The K R channel was active at > 10 −5 M Ca 2+ , and was blocked by 4‐aminopyridine (4AP). At < 10 −6 M Ca 2+ , the K R channel became inactive, but could be activated by 2‐nicotinamidethyl nitrate (nicorandil), or by 4‐acetamide‐4′‐isothiocyanostilbene‐2,2′‐disulfonic acid (SITS) applied to the pipette solution. It was found that there is a close correlation between the K R channel activity and cell contraction: cells contracted under conditions in which the KR channel became inactive, but were relaxed when the K R channel was active. As the K R channel is highly active in cells in physiological saline, we suggest that it controls the tonus of the coronary artery, as an endogenous dilating factor.