Inactivation of the sodium channel. II. Gating current experiments.
Inactivation of the sodium channel. II. Gating current experiments.
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DOI：
10.1085/jgp.70.5.567
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发表时间：
1977-11
期刊：
影响因子：
--
通讯作者：
Bezanilla F
中科院分区：
文献类型：
--
作者：
Armstrong CM;Bezanilla F
门控电流（IG）与Na通道失活的关系已被研究。IG的任何组分都不具有失活的时间过程;显然很少或没有电荷移动与该步骤相关。尽管如此，灭活通过固定约三分之二的门控电荷来影响IG。固定之后可以测量脉冲期间的ON电荷移动，并将其与脉冲后的OFF电荷进行比较。对于如此短以至于不发生失活的脉冲，OFF：ON比率接近1，并且该比率在与失活平行的时间过程中下降到约三分之一。失活与固定之间的其他相关性是：（a）它们具有相同的电压依赖性;（B）电荷运动随失活恢复的时间过程而恢复。我们解释这意味着，固定化的电荷慢慢返回到“关闭”的位置与失活恢复的时间过程中，产生的小电流丢失在基线噪声。在-150 mV下，恢复非常迅速，并且固定的电荷在其返回到断开位置时形成电流的明显的慢分量。在链霉蛋白酶破坏失活后，没有电荷的固定。提出了一个模型，其中失活获得其电压依赖性耦合到激活门。
Gating current (Ig) has been studied in relation to inactivation of Na channels. No component of Ig has the time course of inactivation; apparently little or no charge movement is associated with this step. Inactivation nonetheless affects Ig by immobilizing about two-thirds of gating charge. Immobilization can be followed by measuring ON charge movement during a pulse and comparing it to OFF charge after the pulse. The OFF:ON ratio is near 1 for a pulse so short that no inactivation occurs, and the ratio drops to about one-third with a time course that parallels inactivation. Other correlations between inactivation and immobilization are that: (a) they have the same voltage dependence; (b) charge movement recovers with the time coures of recovery from inactivation. We interpret this to mean that the immobilized charge returns slowly to "off" position with the time course of recovery from inactivation, and that the small current generated is lost in base-line noise. At -150 mV recover is very rapid, and the immobilized charge forms a distinct slow component of current as it returns to off position. After destruction of inactivation by pronase, there is no immobilization of charge. A model is presented in which inactivation gains its voltage dependence by coupling to the activation gate.