Glycogenolysis in the heart and skeletal muscle during stimulation and blocking of cholinergic receptors. I. Action of parasympathicotonic compounds.

In vitro changes in enzymatic activities during phosphorolytic and hydrolytic glycogenolysis in the working heart and resting skeletal muscle were studied after intravenous injection of parasympathicotonic compounds. Acetylcholine increased phosphorolytic activity in both muscles and at the same time decreased hydrolytic activity. Since administration of selectively parasympathicotonic compounds such as pilocarpine, furmethide and bethanechol did not produce similar effects, the observed action of acetylcholine does not seem to be connected with the muscarinic receptor. Experiments with isolated muscles (cardiac, skeletal) incubated with acetylcholine gave no results indicating a direct action of acetylcholine on the investigated enzymatic processes.