Keynes R D, Greeff N G, Forster I C, Bekkers J M
Station Biologique de Roscoff, France.
Proc Biol Sci. 1991 Nov 22;246(1316):135-40. doi: 10.1098/rspb.1991.0135.
The effect of tetrodotoxin (TTX) on the sodium gating current in the squid giant axon was examined by recording the current that flowed at the pulse potential at which the ionic current fell to zero, first in the absence and then in the presence of TTX. The addition of 1 microM TTX to the bathing solution had no consistent effect on the size of the initial peak of the gating current, but resulted in small changes in the timecourse of its subsequent relaxation which were mainly caused by a reduction of about one quarter in the component that has a delayed onset and may possibly arise from changes in the state of ionization of groups in the channel wall when the lumen fills with water. Our findings suggest that the binding of TTX at the outer face of the sodium channel does not interfere with the mechanisms of activation and inactivation by the voltage sensors, but has an allosteric effect on the access of internal cations to the inside of the channel.
通过记录在离子电流降至零时的脉冲电位下流动的电流，首先在不存在河豚毒素（TTX）的情况下，然后在存在TTX的情况下，研究了河豚毒素（TTX）对乌贼巨大轴突中钠门控电流的影响。向浴液中添加1微摩尔TTX对门控电流初始峰值的大小没有一致的影响，但导致其随后松弛的时间进程发生小的变化，这主要是由延迟开始且可能源于管腔充满水时通道壁中基团电离状态变化的成分减少约四分之一引起的。我们的研究结果表明，TTX在钠通道外表面的结合不会干扰电压传感器的激活和失活机制，但对内部阳离子进入通道内部具有变构效应。
