THE EFFECTS OF CORONARY OCCLUSION IN DOGS TREATED WITH RESERPINE AND IN DOGS TREATED WITH PHENOXYBENZAMINE

¹ Laboratory of Chemical Pharmacology, National Heart Institute and Laboratory of Pathology and Histochemistry, National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Bethesda, Maryland

The anterior descending coronary artery was ligated by the two-stage occlusion procedure of Harris in 17 dogs in which the myocardium had been depleted of norepinephrine by reserpine and in 3 dogs pretreated with the adrenergic blocking agent phenoxybenzamine. Two dogs pretreated with reserpine and 1 dog pretreated with phenoxybenzamine died from ventricular fibrillation shortly after occlusion. The surviving dogs all developed the spontaneous ventricular ectopic activity and prolonged myocardial hypersensitivity characteristic after infarction. There was no significant difference in the elevations in serum enzyme levels nor in either the gross or histological appearance of the infarets in treated and in nontreated dogs. Frozen sections stained for neutral fat with Oil red O showed the usual fatty changes around the infarct. It is unlikely that release of norepinephrine from the infarcted area during necrosis has a significant role either in the usual development of spontaneous arrhythmias and myocardial hypersensitivity or in the deposition of neutral fat around the boundary of the infarct.

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