The Effect of Glucagon on the Coronary Circulation in Man

Glucagon, 300 µg/ minute, was infused intravenously over 15 minutes in 27 subjects. The patients were divided into three groups: group I, patients without heart disease; group II, patients with arteriosclerotic heart disease; and group III, patients with congestive heart failure. Hemodynamic measurements included observations on myocardial blood flow using bolus injections of 84 rubidium and a coincidence counting technic. Myocardial oxygen consumption was determined after coronary sinus intubation in nine of the 27 patients. Significant increases were noted in heart rate, mean arterial pressure, tension-time index/minute and left ventricular work. Myocardial blood flow increased significantly while myocardial oxygen extraction remained constant suggesting that the augmentation in blood flow was sufficient to meet the increased myocardial demands for oxygen. The effects of glucagon on the coronary circulation resemble that of isoproterenol rather than norepinephrine without, however, leading to the production of arrhythmias seen with these catecholamines.