中华大蟾蜍卵母细胞质膜的外向整流型钾离子通道  

A VOLTAGE-DEPENDENT POTASSIUM CHANNEL OF OUTWARD RECTIFIER TYPE IN PLASMA MEMBRANE OF OOCYTE FROM TOAD, BUFO BUFO GARGARIZANS

作　　者：姚永[1] 顾全保[2] 朱辉[1] 包永德[1] 左嘉客[2] 

机构地区：[1]中国科学院上海生理研究所 [2]中国科学院上海细胞生物研究所,上海200031

出　　处：《生理学报》1992年第5期461-469,共9页Acta Physiologica Sinica

摘　　要：我们用电压箝方法研究了中华大蟾蜍卵母细胞的膜生理特性。发现卵母细胞膜去极化至-30mV及更偏正时,有一持续的外向电流出现,该电流与去极化程度约呈正比增加,当膜电位箝在20mV时其峰值达3.7±1.4μA。该电流被钾离子通道拮抗剂TEA和4-AP抑制,TEA半抑制浓度为2.6mmol/L。氯通道拮抗剂9-AC(2.5mmol/L)无抑制作用。无钙的或钙离子浓度增加三倍的胞外灌流液均对该电流无影响、该外向电流的逆转电位随胞外钾离子浓度的改变而变化。胞外钾离子浓度增加十倍,逆转电位约增加47.3mV,而胞外钠、钙或氯离子浓度的改变对逆转电位基本上无影响,因此该电流可被认为主要是电压依赖性钾离子流。取自冬眠蟾蜍的卵母细胞经孕酮诱发成熟后,电压依赖性钾离子流减小,仅为原来的1/20-1/30,而取自全年在高温饲养的蟾蜍的卵母细胞经孕酮处理后未见成熟,其电压依赖性钾离子流仅减小至原来的三分之一。Membrane properties of the fully-grown oocytcs from toad, Bufo bufo gar-garizans, were studied by using voltage-clamp technique. It was found that asustained outward cuttrnt was elicited by membrane depolarization to--30 mVor more positive value. The increase of the current was nearly proportional tothe degree of depolarization. The peak value of the current ranged 2--5 μA ata membrane potential of 20 mV in oocytes from different toads. The currentwas inhibited by antagonists of potassium channel, TEA and 4--AP. The con-centration of TEA capable of inhibiting half of the current was 2.6 mmol/L. Chlo-ride channel antagonist 9--AC (2.5 mmol/L) had no effect on the current. Triplethe extracellular calcium concentration did not show any effect either. The re-versal potential of the current varied with an increase of 47.3mV per decade changeof the extracellular potassium concentration. Changing extracellular concen-tration of sodium or chloride did not shift the revelsal potential. It was concludedthat the outward current was a voltage-activated potassium current. The voltage-dependent potassium current decreased after treatment of the oocytes with proges-terone to a state of maturation. A large decrease of the current (to about 1/20 ofthe control) occurred to the oocytes obtained from hibernating toads while a lessstriking decrease of the current (to about 1/3 of the control) was observed in theoocytes from toads all year round reared at 25--30℃.

关 键 词：钾通道 中华大蟾蜍 卵母细胞 

分 类 号：Q959.530.5[生物学—动物学]