Identification of calcium-activated potassium channels in cultured equine sweat gland epithelial cells
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摘要The patch-clamp recording technique was used to examine the properties of the K+ channels in cultured equine sweat gland epithelial cells. With symmetric K+ solutions (140 mM), a single population of K+ channels was identified with a slope conductance of 187 pS and a reversal potential of around 0 mV. The channel was selective for K+ over Na+. Channel activity was increased by membrane depolarization. A 10-fold increase in [Ca2+], produced an approximate 60 mV negative shift in the open state probability (P-open)-voltage curve. Externally applied tetraethylammonium ions (TEA(+)) caused a rapid and flickery block of the channel and reduced the unitary current amplitude. TEA(+) bound to the blocking site with stoichiometry of 1:1 and with a dissociation constant (K-d) of 186 +/- 27 mu M at +40 mV. A weak voltage dependence of K-d was observed. Iberiotoxin (100 nM) reduced P-open but had no effect on single-channel conductance. Neither glibenclamide (10 mu M) nor intracellular adenosine 5'-triphosphate (ATP, 1 mM) altered channel activity. In addition, ATP, when applied extracellularly, transiently activated the channel by increasing P-open. Channel activity was low around the resting membrane potential in the intact epithelia, indicating that these channels might not contribute to the resting K+ conductance. However, the channel could be activated in a regulated manner. The K+ channels may play a role in transepithelial fluid secretion in sweat gland.
著者Huang Y, Ko WH, Chung YW, Wong PYD
期刊名稱Experimental Physiology
出版年份1999
月份9
日期1
卷號84
期次5
出版社CAMBRIDGE UNIV PRESS
頁次881 - 895
國際標準期刊號0958-0670
電子國際標準期刊號1469-445X
語言英式英語
Web of Science 學科類別Physiology; PHYSIOLOGY

上次更新時間 2020-26-10 於 01:24