Zefirov A L, Khalilov I A, Khamitov Kh S
Neirofiziologiia. 1987;19(4):467-73.
Evoked electrical responses of nerve endings were recorded in experiments on frog cutaneous-pectoris muscle under visual control. During superfusion by Ca2+-free solution with tubocurarine a late inward current was found in the evoked response of nerve endings recorded by CaCl2 filled electrode. With addition of the external solution of 4-aminopyridine the late current was changed into an outward one. This outward current depended on Ca2+ concentration in the electrode, decreased after local increase of K+ concentration and was abolished by Co2+ ions. Local ionophoretic application of tetraethyl-ammonium eliminated the outward current and revealed a strong and prolonged inward current. Similar currents were recorded by microelectrodes filled with SrCl2, BaCl2 and MgCl2. It is concluded that the late inward current is carried through potential-dependent calcium channels, while the late outward one--through Ca2+-activated K+ channels. The ratio of calcium and Ca2+-activated potassium currents in motor nerve endings and their role in the transmitter release are discussed.
在视觉控制下，对青蛙皮肤 - 胸肌进行实验，记录神经末梢的诱发电反应。在用含筒箭毒碱的无钙溶液进行灌流期间，在用氯化钙填充的电极记录的神经末梢诱发反应中发现了一个晚期内向电流。加入4 - 氨基吡啶的外部溶液后，晚期电流转变为外向电流。这种外向电流取决于电极中的钙离子浓度，在局部钾离子浓度增加后减小，并被钴离子消除。局部离子电泳施加四乙铵消除了外向电流，并揭示了一个强烈且持久的内向电流。用填充有氯化锶、氯化钡和氯化镁的微电极记录到了类似的电流。得出的结论是，晚期内向电流通过电压依赖性钙通道传导，而晚期外向电流通过钙激活钾通道传导。讨论了运动神经末梢中钙电流和钙激活钾电流的比例及其在递质释放中的作用。
