小龙虾巨轴突中门控电流的一个缓慢成分类似于失活电荷移动。
A slow component of gating current in crayfish giant axons resembles inactivation charge movement.
作者信息
Swenson R P
出版信息
Biophys J. 1983 Mar;41(3):245-9. doi: 10.1016/S0006-3495(83)84434-8.
Recent experimental evidence from a number of preparations indicates that sodium channel inactivation may be intrinsically voltage sensitive. Intrinsically voltage sensitive inactivation should produce a charge movement. Crayfish giant axons provide a unique opportunity to reexamine the slower components of gating currents (Ig) for a contribution from inactivation (Igh). In reference to other axon preparations, this preparation has relatively rapid inactivation, and steady-state inactivation has a comparatively steep voltage dependence. As predicted by a two-state scheme for voltage-sensitive sodium channel inactivation, Ig in crayfish axons includes a slow component with time constant comparable to the time constant of decay of the sodium current. Allowing for some delay in its onset (60 microseconds), inactivation as described by this slow component of Ig carries roughly the amount of charge predicted by the voltage dependence of inactivation.
来自多种实验制剂的最新实验证据表明，钠通道失活可能本质上对电压敏感。本质上对电压敏感的失活应该会产生电荷移动。小龙虾巨轴突提供了一个独特的机会，可以重新审视门控电流（Ig）的较慢成分，以确定失活（Igh）的贡献。与其他轴突制剂相比，该制剂具有相对较快的失活，并且稳态失活具有相对陡峭的电压依赖性。正如电压敏感钠通道失活的双态模型所预测的那样，小龙虾轴突中的Ig包括一个慢成分，其时间常数与钠电流衰减的时间常数相当。考虑到其起始存在一些延迟（60微秒），由Ig的这个慢成分描述的失活携带的电荷量大致与失活的电压依赖性所预测的电荷量相同。
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