Effect of beta adrenergic blockade on the cardiovascular dynamics

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Abstract
The effect of propranolol on the cardiovascular dynamics was studied in anesthetized dogs. The intravenous administration of graded doses of propranolol decreased heart rate, myocardial contractile force, and cardiac output, whereas left ventricular end-diastolic pressure, left atrial pressure, pulmonary arterial pressure, and total and pulmonary peripheral resistances increased significantly. It was also found that propranolol significantly depresses left ventricular function curves. Mean systemic arterial pressure decreased only when large doses of propranolol were given. The magnitude of these hemodynamic changes was essentially proportional to the dose of propranolol given. Propranolol blocked or decreased the hemodynamic actions of isoproterenol markedly. However, larger doses of isoproterenol always surmounted the beta receptor blocking action of propranolol. It is concluded that a significant degree of beta adrenergic blockade with propranolol depresses the cardiac performance in dogs.