INWARD RECTIFICATION IN RAT CEREBRAL ARTERIOLES - INVOLVEMENT OF POTASSIUM-IONS IN AUTO-REGULATION
INWARD RECTIFICATION IN RAT CEREBRAL ARTERIOLES - INVOLVEMENT OF POTASSIUM-IONS IN AUTO-REGULATION
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DOI：
10.1113/jphysiol.1988.sp017299
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发表时间：
1988-10-01
影响因子：
5.5
通讯作者：
SILVERBERG, GD
中科院分区：
文献类型：
--
作者：
EDWARDS, FR;HIRST, GDS;SILVERBERG, GD
本文测定了大鼠大脑中动脉发出的小动脉近、远段的静息膜电位。近端节段具有稳定的膜电位，平均值为-69 mV。远段膜电位负性较小，常不稳定。当细胞外钾离子浓度（[K+]o）增加时，微动脉近端呈去极化，远端呈超极化。当[K+]o降低时，近端和远端动脉均发生去极化，近端动脉的变化更明显。近端段的小动脉的膜显示向内整流在电位接近休息;向内整流在远端段的小动脉，当检测到，是不太明显。通过改变细胞外K+浓度，可以改变近端小动脉内向整流的激活曲线。[K+]o的减少导致激活曲线移动到这样的负电位，内向整流器不再有助于静息电导。增加[K+]o改变了微动脉远端向内整流的激活曲线，使更多的K+电流在接近静息电位时流动。同时膜电位超极化。结果进行了讨论，在自动调节的变化发生以下的K+浓度的脑脊液中的变化。
The resting membrane potentials of proximal and distal segments of the arterioles which arise from the rat middle cerebral artery were determined. Proximal segments had stable membrane potentials with a mean value of -69 mV. The membrane potentials of distal segments were less negative and often unstable. When the extracellular concentration of potassium ions ([K+]o) was increased proximal segments of arteriole were depolarized whereas distal ones were hyperpolarized. When [K+]o was decreased both proximal and distal segments were depolarized, the changes being more marked in proximal arterioles. The membranes of proximal segments of arteriole displayed inward rectification at potentials near rest; inward rectification in distal segments of arteriole, when detected, was less pronounced. The activation curve for inward rectification in proximal segments of arteriole was changed by changing the extracellular concentration of K+. A reduction in [K+]o caused the activation curve to move to such negative potentials that the inward rectifier no longer contributed to the resting conductance. Increasing [K+]o changed the activation curve for inward rectification in distal segments of arteriole so that more K+ current flowed at potentials near resting. At the same time the membrane potential hyperpolarized. The results are discussed in relation to autoregulatory changes which occur following changes in the K+ concentration of cerebrospinal fluid.