Potassium current and the effect of cesium on this current during anomalous rectification of the egg cell membrane of a starfish.
Potassium current and the effect of cesium on this current during anomalous rectification of the egg cell membrane of a starfish.
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DOI：
10.1085/jgp.67.6.621
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发表时间：
1976-06
期刊：
影响因子：
--
通讯作者：
Rosenthal NP
中科院分区：
文献类型：
--
作者：
Hagiwara S;Miyazaki S;Rosenthal NP
用电压钳技术分析了海星卵细胞膜钾电流异常整流和内向整流过程中膜电流的动力学。整流具有瞬时和时间相关的分量。对于负电压脉冲，K电导的时间依赖性增加以及对于正脉冲，电导的减少遵循一级动力学。稳态电导随着膜电位变得更负而增加，并且在比K平衡电位V（K）更负约-40 mV处达到饱和值。整个K电导可以表示为g（K）. n; g g（K）表示依赖于V-V（K）和[K +] o的与时间无关的电导的分量，并且n是无量纲数（1大于或等于n大于或等于0）并且由仅依赖于V-V（K）的两个速率常数确定。Cs+不携带任何显著的电流通过K通道，但在低浓度下在外部介质中阻断通道。随着膜电位变得更负，阻断效应增加，并且外部Cs+的电位依赖性阻断也具有瞬时和时间依赖性成分。
The kinetics of the membrane current during the anomalous or inward- going rectification of the K current in the egg cell membrane of the starfish Mediaster aequalis were analyzed by voltage clamp. The rectification has instantaneous and time-dependent components. The time- dependent increase in the K conductance for the negative voltage pulse as well as the decrease in the conductance for the positive pulse follows first-order kinetics. The steady-state conductance increases as the membrane potential becomes more negative and reaches the saturation value at about -40 mV more negative than the K equilibrium potential, V(K). The entire K conductance can be expressed by g(K).n; g g(K) represents the component for the time-independent conductance which depends on V-V(K) and [K+]o, and n is a dimensionless number (1 is greater than or equal to n is greater than or equal to 0) and determined by two rate constants which depend only on V-V(K). Cs+ does not carry any significant current through the K channel but blocks the channel at low concentration in the external medium. The blocking effect increases as the membrane potential is made more negative and the potential-dependent blocking by the external Cs+ also has instantaneous and time-dependent components.