[Effect of nitroglycerin on the ino- and chronotropic function of the myocardium]

It has been shown in experiments on conscious cats that nitroglycerin exerts a cardiostimulatory effect on the myocardium. The positive inotropic effect of nitroglycerin is associated with the two processes, catecholamine release from sympathetic nerve terminals and blockade of phosphodiesterase activity. The positive chronotropic effect arises from the indirect sympathomimetic properties of nitroglycerin. In addition to the effects listed, nitroglycerin reduces the intensity of the cardiac chronotropic reactions induced by isoproterenol and produces a direct inhibitory action on the myocardium. The implication of the nitroglycerin effects in the realization of its antianginal action is discussed.