Effects of glucagon on myocardial metabolism in patients with and without coronary artery disease.

The metabolic effects of glucagon on the heart were studied in subjects with and without coronary artery disease. In both groups, a moderate rise in the arterial glucose level occurred with practically unchanged glucose uptake by the myocardium. Myocardial oxygen extraction was also unchanged in both groups of subjects. In individuals with normal coronary arteries, myocardial extraction ratio of lactate was normal before and unchanged after glucagon administration. In patients with significant coronary artery disease, mean extraction ratio of lactate was very low before glucagon and increased markedly following its administration. Seven of 18 patients had production of lactate by the myocardium before glucagon, and this reverted to lactate extraction 5 min after glucagon administration. Left ventricular work index was found to increase