The effect of 2-methylnaphthoquinone on the parasympathetic innervation and cardiac activity of cold-blooded animals

Summary When acting upon the isolated heart or administered into the blood flow, concentrations of 2-methylnaphthoquinone (1: 50,000–1: 100,000) provoke a decrease and disappearance, first of the inotropic component of the parasympathetic effect, then the vagal arrest, and, lastly, the inhibition of chronotropic component. These changes are caused by the disturbance of the acetylcholine metabolism and the liberation of this substance in the nerve endings of the vagus. Besides, large concentrations (1: 10,000) render a nonspecific altering effect on the cardiac elements.(Presented by Active Member of the AMN SSSR V. V. Parin) Translated from Byulleten Èksperimental'noi Biologii i Meditsiny Vol. 49, No. 4, pp. 71–75, April, 1960