来自兔主动脉的一种钙激活钾通道：克罗卡林对其的调节作用。

A Ca2+-activated K+ channel from rabbit aorta: modulation by cromakalim.

作者信息

Gelband C H, Lodge N J, Van Breemen C

机构信息

Department of Pharmacology, University of Miami School of Medicine, FL 33101.

出版信息

Eur J Pharmacol. 1989 Aug 22;167(2):201-10. doi: 10.1016/0014-2999(89)90580-3.

DOI:10.1016/0014-2999(89)90580-3

PMID:2591475

Abstract

A large conductance Ca2+-activated K+ channel from rabbit aorta was incorporated into planar lipid bilayers. This channel had a conductance of 337 +/- 7 pS in symmetrical 250 mM KCl solutions and had a Na+/K+ permeability ratio of less than 0.04. In asymmetrical solutions containing 300 mM KCl cis (intracellular), 100 mM KCl trans (extracellular) or 100 mM KCl cis 500 mM KCl trans, the reversal potentials for the channel were -30 and +46 mV, respectively. This channel possessed voltage-dependent activation and cis (intracellular) Ca2+ sensitivity. Cromakalim (50 nM) added to the trans side of the bilayer significantly increased the Popen by 56% from 0.09 +/- 0.01 to 0.14 +/- 0.01 (P less than 0.01) at -40 mV without altering the single channel conductance. This effect was dose-dependent, increasing at higher cromakalim concentrations. The primary effect of cromakalim was to decrease the tau slow of the channel closed state from 266 +/- 32 to 147 +/- 17 ms which is sufficient to account for the increase in Popen of the channel in the presence of cromakalim.

摘要

将兔主动脉的一种大电导钙激活钾通道整合到平面脂质双分子层中。该通道在对称的250 mM KCl溶液中的电导为337±7 pS，钠/钾渗透率比值小于0.04。在含有300 mM KCl顺式（细胞内）、100 mM KCl反式（细胞外）或100 mM KCl顺式、500 mM KCl反式的不对称溶液中，该通道的反转电位分别为-30和+46 mV。该通道具有电压依赖性激活和顺式（细胞内）钙敏感性。添加到双分子层反式侧的克罗卡林（50 nM）在-40 mV时使开放概率（Popen）从0.09±0.01显著增加56%至0.14±0.01（P<0.01），而不改变单通道电导。这种效应呈剂量依赖性，在较高的克罗卡林浓度下增加。克罗卡林的主要作用是将通道关闭状态的时间常数（tau slow）从266±32 ms降低到147±17 ms，这足以解释在存在克罗卡林的情况下通道开放概率的增加。