Schauf C L, Bullock J O, Pencek T L
Biophys J. 1977 Jul;19(1):7-28. doi: 10.1016/S0006-3495(77)85559-8.
Sodium currents after repolarization to more negative potentials after initial activation were digitally recorded in voltage-clamped Myxicola axons compensated for series resistance. The results are inconsistent with a Hodgkin-Huxley-type kinetic scheme. At potentials more negative than -50 mV, the Na+ tails show two distinct time constants, while at more positive potentials only a single exponential process can be resolved. The time-course of the tail currents was totally unaffected when tetrodotoxin (TTX) was added to reduce gNa to low values, demonstrating the absence of any artifact dependent on membrane current. Tail currents were altered by [Ca++] in a manner consistent with a simple alteration in surface potential. Asymmetry current "off" responses are well described by a single exponential. The time constant for this response averaged 2.3 times larger than that for the rapid component of the Na+ repolarization current and was not sensitive to pulse amplitude or duration, although it did vary with holding potential. Other asymmetry current observations confirm previous reports on Myxicola.
在初始激活后复极化到更负电位时的钠电流，在补偿了串联电阻的电压钳制的黏液虫轴突中进行了数字记录。结果与霍奇金 - 赫胥黎型动力学方案不一致。在比 -50 mV更负的电位下，钠尾电流显示出两个不同的时间常数，而在更正的电位下，只能分辨出一个单一的指数过程。当加入河豚毒素（TTX）将gNa降低到低值时，尾电流的时间进程完全不受影响，这表明不存在任何依赖于膜电流的伪迹。尾电流受[Ca++]的影响，其方式与表面电位的简单变化一致。不对称电流“关闭”响应可以用一个单一的指数很好地描述。该响应的时间常数平均比钠复极化电流快速成分的时间常数大2.3倍，并且对脉冲幅度或持续时间不敏感，尽管它确实随保持电位而变化。其他不对称电流观察结果证实了先前关于黏液虫的报道。
