Effect of some surfactants on neuromuscular transmission of excitation

Abstract

The effect of the sodium salts of bile acids (BA), saponin, and Tween 80 on end-plate potentials (EPPs) of the myoneural junction of the frog sartorius muscle was investigated by a microelectrode method. Salts of BA in a concentration of 10−5 g/ml had no appreciable effect on these potentials, but with an increase in their concentration to 10−4 g/ml the amplitude of the EPPs was increased by 1.5–3 times. During the action of BA in a concentration of 10−3 g/ml the same effect was observed, but there was a much more rapid increase in amplitude of the EPPs followed by a decrease. Saponin and Tween 80 were less effective as regards the EPPs, but they did affect the contractile activity of the muscle. The increase in amplitude of EPPs under the influence of the substances tested is due principally, it is suggested, to stimulation of the liberation of acetylcholine by nerve terminals.