EFFECTS OF GALLAMINE TRIETHIODIDE ON MEMBRANE CURRENTS IN AMPHIBIAN AND MAMMALIAN PERIPHERAL-NERVE

  • 1 January 1981
    • journal article
    • research article
    • Vol. 217  (3) , 719-726
Abstract
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 [Rana pipiens] and mammalian [rat] nerve fibers, whether applied externally or internally. With external application, galamine (0.1-10.0 mM) is about 5 times more potent than tetraethylammonium chloride in blocking the delayed K+ conductance (gK), where this is present. The Na+ conductance is completely unaffected by external gallamine in both species. Internal application of gallamine to myelinated nerve fibers slows Na+ inactivation. At positive potentials, gallamine can enter Na+ channels and occlude them, thereby almost eliminating outward Na+ currents. In rat fibers, a significant fraction of the Na+ channels fail to inactivate and large inward Na+ tail currents occur upon repolarization. The general consequences of these findings with regard to possible side-effects in gallamine-paralyzed preparations is discussed.