BLOCK OF SODIUM CONDUCTANCE AND GATING CURRENT IN SQUID GIANT-AXONS POISONED WITH QUATERNARY STRYCHNINE
BLOCK OF SODIUM CONDUCTANCE AND GATING CURRENT IN SQUID GIANT-AXONS POISONED WITH QUATERNARY STRYCHNINE
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DOI：
10.1016/s0006-3495(79)85202-9
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发表时间：
1979-01-01
影响因子：
3.4
通讯作者：
ALMERS, W
中科院分区：
文献类型：
--
作者：
CAHALAN, MD;ALMERS, W
季士的宁块钠通道从轴浆侧，可能是通过插入到内通道口。阻滞是强烈的电压依赖性，在去极化中比在静息轴突中更明显。采用电位阶跃法调节阻滞水平，观察士的宁对+50和-70 mV钠电流和门控电流的影响。根据最简单的可能模型分析数据，其中只有开放通道可以接收和保留士的宁分子。调查结果如下：士的宁的阻断和失活彼此相似，并且士的宁对钠电流和门控电流的阻断以非常相似的时间过程发生。数据支持这样的假设，即内源性阻断颗粒通过将其自身插入钠通道的内口而引起失活。季士的宁可能作为一种人工替代品的假设内源性阻断颗粒。鱿鱼轴突中至少90%的快速不对称位移电流是钠通道门控电流，因为季士的宁可以同时阻断90%的位移电流和钠电流。
Quaternary strychnine blocks sodium channels from the axoplasmic side, probably by insertion into the inner channel mouth. Block is strongly voltage dependent, being more pronounced in depolarized than in resting axons. Using potential steps to modulate the level of block, the strychnine effects on sodium and gating currents at +50 and -70 mV were investigated. The data were analyzed in terms of the simplest possible model, wherein only an open channel may receive and retain a strychnine molecule. The findings were: block by strychnine and inactivation resemble each other, and block of sodium and gating currents by strychnine happen with closely similar time-courses. The data support the hypothesis wherein an endogenous blocking particle causes inactivation by inserting itself into the inner mouth of the sodium channel. Quaternary strychnine may act as an artificial substitute for the hypothetical endogenous blocking particle. At least 90% of the rapid asymmetrical displacement current in squid axons is sodium channel gating current, inasmuch as quaternary strychnine can block 90% of the displacement current simultaneously with sodium current.