Campbell D T, Hille B
J Gen Physiol. 1976 Mar;67(3):309-23. doi: 10.1085/jgp.67.3.309.
Na channels of frog skeletal muscle are studied under voltage clamp and their properties compared with those of frog myelinated nerve. A standard mathematical model is fitted to the sodium currents measured in nerve and in muscle to obtain a quantitative description of the gating kinetics. At 5 degrees C the kinetics in frog nerve and skeletal muscle are similar except that activation proceeds five times faster in nerve. Block of Na channels by saxitoxin is measured in nerve and in muscle. The apparent dissociation constants for the inhibitory complex are about 1 nM and not significantly different in nerve and muscle. Block of Na channels by external protons in muscle is found to have an apparent pKalpha of 5.33 and a voltage dependence corresponding to action of 27% of the membrane potential drop. Both values are like those for nerve. Shift of the peak sodium permeability-membrane potential curve with changes of external pH and Ca++ are found to be the same in nerve and muscle. It is concluded that Na channels of nerve and muscle are nearly the same.
在电压钳条件下研究了青蛙骨骼肌的钠通道，并将其特性与青蛙有髓神经的钠通道特性进行了比较。用一个标准的数学模型拟合在神经和肌肉中测得的钠电流，以获得门控动力学的定量描述。在5摄氏度时，青蛙神经和骨骼肌中的动力学相似，只是神经中的激活速度快五倍。在神经和肌肉中测量了石房蛤毒素对钠通道的阻断作用。抑制复合物的表观解离常数约为1 nM，在神经和肌肉中无显著差异。发现肌肉中外部质子对钠通道的阻断作用的表观pKα为5.33，其电压依赖性相当于膜电位降的27%的作用。这两个值与神经中的值相似。发现神经和肌肉中随着外部pH值和Ca++的变化，峰值钠通透性-膜电位曲线的移动是相同的。得出的结论是，神经和肌肉的钠通道几乎相同。
