Ramón F, Moore J W
Am J Physiol. 1978 May;234(5):C162-9. doi: 10.1152/ajpcell.1978.234.5.C162.
Some characteristics of ephaptic transmission of action potentials were investigated with squid giant axons. For these studies two isolated axons were placed side by side or, on occasion, a single long axon was looped to form an "ephapse" between the axon trunk and one of its main branches. Extracellular potentials measured adjacent to axons surrounded by a very restricted volume of liquid ranged up to 80 mV in magnitude and had a shape similar to that of the membrane current. Intracellular records of the same axon regions show small voltage deflections; however, the transmembrane voltage (Vm = Vi - Vo) has the appearance of normally propagated action potentials. Ephaptic transmission of action potentials is possible when the ephaptic region is submerged in oil, as well as when the region is immersed in low-calcium solutions. When the speed of the propagated action potential is lowered by replacing the normal artifical seawater (ASW) with low-sodium ASW, some ephaptic effects are enhanced. It is concluded that in regions in which axons are confined by restricted extracellular volume, the large extracellular voltage changes arising during the passage of an action potential in one can cause ephaptic excitation in another.
利用枪乌贼巨大轴突对动作电位的电突触传递的一些特性进行了研究。在这些研究中，将两根分离的轴突并排放置，或者偶尔将一根长轴突环绕起来，在轴突主干与其一个主要分支之间形成一个“电突触”。在被非常有限体积的液体包围的轴突附近测量的细胞外电位幅度高达80 mV，其形状与膜电流相似。同一轴突区域的细胞内记录显示出小的电压偏转；然而，跨膜电压（Vm = Vi - Vo）具有正常传播的动作电位的外观。当电突触区域浸没在油中时，以及当该区域浸入低钙溶液中时，动作电位的电突触传递都是可能的。当用低钠人工海水（ASW）替代正常的人工海水来降低传播的动作电位的速度时，一些电突触效应会增强。得出的结论是，在轴突被有限的细胞外体积限制的区域中，一个轴突中动作电位通过时产生的大的细胞外电压变化可在另一个轴突中引起电突触兴奋。
