Kukita F, Yamagishi S
J Membr Biol. 1983;75(1):33-44. doi: 10.1007/BF01870797.
The excitation of the squid giant axon was analyzed under an outward water flow through the membrane product by an osmotic gradient. The outward water flow made an undershoot of the action potential larger by about 25 mV without decreasing its peak largely. It also made EK more negative but not ENa. The effect of the outward water flow was specific for the potassium channel. The outward current increased and its decline during a long-lasting depolarization became less prominent under the outward water flow. At the same time, inward tail currents for the potassium channel decreased extraordinarily without a large change in the time course. The potassium conductance had a marked rectification in the direction of the water flow. The undershoot of the action potential under the outward water flow was very sensitive to potassium ions in the external solution. Eight mM KCl was effective to diminish the undershoot and to restore the change in EK by about 60% but gave no effect on the reduced tail current. The outward water flow effect can be explained not only by the change in a local concentration of potassium ions at the mouths of the potassium channel due to a sieving but also by the rectification in a hydrodynamic manner.
在通过渗透梯度产生的膜产物向外水流作用下，对鱿鱼巨轴突的兴奋进行了分析。向外水流使动作电位的负后电位增大了约25mV，而其峰值没有大幅降低。它还使EK更负，但ENa没有变化。向外水流的作用对钾通道具有特异性。在向外水流作用下，向外电流增加，并且在长时间去极化期间其衰减变得不那么明显。与此同时，钾通道的内向尾电流异常减少，而时间进程没有大的变化。钾电导在水流方向上有明显的整流作用。向外水流作用下动作电位的负后电位对外界溶液中的钾离子非常敏感。8mM KCl可有效减少负后电位，并使EK的变化恢复约60%，但对降低的尾电流没有影响。向外水流的作用不仅可以通过由于筛分导致钾通道口处局部钾离子浓度的变化来解释，还可以通过流体动力学方式的整流来解释。
