The Action of Nitroglycerine and Dipyridamole in Normal and Ischaemic Dog Heart

Abstract

Network and post‐network resistances were measured together with heat clearance and heat production in the myocardium. Nitroglycerine dilated all resistance vessels but was twice as effective on network as compared with post‐network vessels. Dipyridamole dilated network and post‐network vessels equally. Nitroglycerine had no effect on heat clearance or heat production in ischaemic myocardium. Dipyridamole increased heat clearance in normal but not in ischaemic myocardium. Dipyridamole depressed heat production in normal and ischaemic myocardium. That the clinical effectiveness of nitroglycerine does not depend entirely on its coronary vasodilator properties is confirmed. It is suggested that the action of dipyridamole in depressing myocardial heat production may be due to an action on the efficiency of oxygen utilization during cardiac contraction.