Smith K J, Schauf C L
J Pharmacol Exp Ther. 1981 Jun;217(3):719-26.
Gallamine triethiodide ("Flaxedil") is in common clinical and experimental use specifically to block neuromuscular transmission. Voltage-clamp studies show that gallamine also has direct effects on amphibian and mammalian nerve fibers, whether applied externally or internally. With external application, gallamine (0.1-10.0 mM) is about 5 times more potent than tetraethylammonium chloride in blocking the delayed potassium conductance (gk), where this is present. The sodium conductance is completely unaffected by external gallamine in both species. Internal application of gallamine to myelinated nerve fibers slows sodium inactivation. In addition, at positive potentials, gallamine can enter Na+ channels and occlude them, thereby almost eliminating outward sodium currents. In rat fibers, a significant fraction of the sodium channels fail to inactivate and thus large inward sodium tail currents occur upon repolarization. The general consequences of these findings with regard to possible "side-effects: in gallamine-paralyzed preparations is discussed.
三碘季铵酚（“弗来西德”）在临床和实验中常用于阻断神经肌肉传递。电压钳研究表明，无论外用还是内用，三碘季铵酚对两栖动物和哺乳动物神经纤维都有直接作用。外用时，三碘季铵酚（0.1 - 10.0 mM）在阻断延迟钾电导（gk，若存在）方面的效力约为氯化四乙铵的5倍。在这两个物种中，钠电导完全不受外用三碘季铵酚的影响。将三碘季铵酚内用于有髓神经纤维会减缓钠失活。此外，在正电位时，三碘季铵酚可进入Na⁺通道并使其堵塞，从而几乎消除外向钠电流。在大鼠纤维中，相当一部分钠通道未能失活，因此复极化时会出现大的内向钠尾电流。本文讨论了这些发现对于三碘季铵酚麻痹制剂中可能出现的“副作用”的总体影响。
