[Mechanism of the inhibitory effect of acetylcholine and its analogs on sarcolemma Na, K-ATPase].

Effect of acetylcholine on Na, K-ATPase from cardiac and skeletal rabbit muscles is studied. The inhibition of the enzyme by acetylcholine was shown to depend on the Na+/K+ ratio and Mg2+ concentration in the incubation medium. The sensitivity of Na, K-ATPase to acetylcholine and its analogues decreased as follows: acetylcholine, propionylcholine butyrylcholine, arecoline, carbacholine, choline. Muscle denervation resulted in 20-fold increase of the enzyme sensitivity to acetylcholine. Preparations of Na, K-ATPase from different muscles have the increasing sensitivity to acetylcholine in the following order: white, mixed, cardiac, denervated muscles.