The combined effect of atropine and β-adrenergic receptor antagonists on left ventricular function and coronary blood flow

Abstract

The effect on the ability of the left ventricle to perform work of two β-adrenergic receptor blocking drugs, dl-propranolol (Inderal) and Ciba 39,089-Ba (Trasicor), with and without atropine, has been studied over a wide range of work. Equipotent β-blocking doses of both drugs were used. Both dl-propranolol and Ciba 39,089-Ba depressed left ventricular function curves and displaced them to the right, indicating a decrease in the ability of the left ventricle to perform work at a given filling pressure. The depressant effect of dl-propranolol was significantly greater than that of an equipotent β-blocking dose of Ciba 39,089-Ba. Both β-antagonists caused a decline in coronary blood flow, in heart rate, and in the rate at which O 2 was extracted from the coronary circulation. Each increased the amount of work done by the myocardium per unit of oxygen extracted from the coronary circulation. The depressant effect of either dl-propranolol or Ciba 39,089-Ba on the ability of the left ventricle to perform work at a given filling pressure was not modified by atropine.