[The effect of carbacholine on spontaneous quantum secretion of a mediator from frog motor nerve endings in the presence of ouabain and in a potassium-free medium].

The carbacholine (Cch) effect on the frequency of miniature end-plate potentials (MEPP) has been studied in the frog muscle in the presence of ouabain and in the potassium-free solution. The depressing presynaptic effect of Cch on the MEPP frequency was eliminated by ouabain, whereas the inactivation of ATPase by the potassium-free solution did not affect the degree of the MEPP frequency decrease. The possibility of the spontaneous quantal release regulation in cholinomimetic drugs by means of the ouabain-sensitive mechanism not related to the pumping function of the Na+, K+ and ATPase active transport is discussed.