The Actions of Organic Nitrates On the Cardiopulmonary and Peripheral Circulations

Abstract

The experimental and clinical evidence for the action of nitrates on the coronary, pulmonary and peripheral circulation has been reviewed. Nitroglycerin as well as the long acting nitrates[long dash]erythrol tetranitrate, (sublingual ETN, Cardilate) pentaerythrol tetranitrate (PETN, Peritrate) and the most recently introduced isosorbide dinitrate (ISDN, Isordil)[long dash]exert a distinct vasodilatory effect not only on the coronary arteries but also on other circulatory compartments. The favorable effect of these nitrates on the anginal syndrome has been demonstrated by both careful symptomatic and objective evaluation utilizing exercise ecg''s and bcg''s. The mechanism of action has, however, not yet been elucidated despite the employment of cardiac and coronary sinus catheterization. The coronary dilatory effect of nitrates is abundantly evident from experimental studies. Nitrates have also been found to affect the pulmonary vascular bed both in patients with coronary disease, left ventricular failure due to hypertensive heart disease and pulmonary hypertension secondary to mitral valvular disease. This has been well demonstrated by cardiac catheterization methods in the case of nitroglycerin and Isordil. Nitroglycerin and the long acting nitrates have also been demonstrated to exert a considerable vasodilatory effect upon the peripheral circulation by means of plethysmographic studies. Further investigations in man are required to elucidate the mechanism of action of nitrates and individual differences.