INWARD RECTIFIER K+ CURRENTS IN SMOOTH-MUSCLE CELLS FROM RAT RESISTANCE-SIZED CEREBRAL-ARTERIES
INWARD RECTIFIER K+ CURRENTS IN SMOOTH-MUSCLE CELLS FROM RAT RESISTANCE-SIZED CEREBRAL-ARTERIES
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DOI：
10.1152/ajpcell.1993.265.5.c1363
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发表时间：
1993-11-01
影响因子：
--
通讯作者：
NELSON, MT
中科院分区：
文献类型：
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作者：
QUAYLE, JM;MCCARRON, JG;NELSON, MT
向内整流的K+通道与膜电位的控制和外部K+诱导的脑小动脉扩张有关。本研究通过Wistar-Kyoto大鼠大脑后动脉分离的单个平滑肌细胞，测量了通过向内整流K+通道的全细胞K+电流。整个电池K+电流-电压关系向内整流。向内电流被记录为负的K+平衡电位，而向外电流很小。当细胞外K+升高时，零电流电位转移到新的K+平衡电位，向内电流电导增加。向内的电流被外部的钡或铯所减少。钡和铯的抑制作用随着膜的超极化而增强。在-60 mV时，钡的半抑制常数为2.2 muM，在23 mV退极化时增加了e倍。我们提供了单个平滑肌细胞内向整流K+电流的第一次直接测量，并表明外部钡离子是这些电流的有效阻断剂。
Inward rectifier K+ channels have been implicatedin the control of membrane potential and external K+induced dilations of small cerebral arteries. In the present study, whole cell K+ currents through the inward rectifier K+ channel were measured in single smooth muscle cells isolated from the posterior cerebral artery of Wistar-Kyoto rats. The whole cell K+ current-voltage relationship showed inward rectification. Inward currents were recorded negative to the K+ equilibrium potential, whereas outward currents were small. When extracellular K+ was elevated, the zero current potential shifted to the new K+ equilibrium potential, and the conductance of the inward cu''ent increased. Inward currents were reduced by external barium or cesium. Inhibition by barium and cesium increased with membrane hyperpolarization. The half-inhibition constant for barium was 2.2 muM at -60 mV, increasing e-fold for a 23-mV depolarization. We provide the first direct measurements of inward rectifier K+ currents in single smooth muscle cells and show that external barium ions are effective blockers of these currents.