Borchard U, Drouin H
Eur J Pharmacol. 1978 Aug 15;50(4):307-16. doi: 10.1016/0014-2999(78)90136-x.
The action of the antituberculous agent ethambutol on the myelinated nerve was studied in two ways: (1) Resting and compound action potentials of the desheathed sciatic nerve were measured; (2) Na+ and K+ currents through the node of Ranvier were investigated by means of the voltage clamp. Reversible dose-dependent decreases of the compound action potential and of the conduction velocity were observed when ethambutol was applied in concentrations of 1--7 mM for 15 min; prolongation up to 60 min caused irreversible changes in membrane function and a decrease in Ca content. Ethambutol induced a hyperpolarizing change of the resting potential. When the nerve was depolarized in Ca2+-free solutions, ethambutol repolarized the nerve membrane. Ethambutol instantly reduced sodium and potassium currents through the nodal membrane. Presumably ethambutol acts primarily as a Ca2+ chelating cation on negative charges at the nerve membrane.
（1）测量去鞘坐骨神经的静息电位和复合动作电位；（2）通过电压钳研究通过郎飞结的钠电流和钾电流。当乙胺丁醇以1-7 mM的浓度作用15分钟时，观察到复合动作电位和传导速度出现可逆的剂量依赖性降低；作用长达60分钟会导致膜功能发生不可逆变化以及钙含量降低。乙胺丁醇引起静息电位的超极化变化。当神经在无钙溶液中去极化时，乙胺丁醇使神经膜复极化。乙胺丁醇可立即减少通过结膜的钠电流和钾电流。推测乙胺丁醇主要作为一种钙螯合阳离子作用于神经膜上的负电荷。
