Studies on the Myocardial Metabolism of Diabetes Mellitus and the Effects of Insulin, Glucocorticoid and Epinephrine on the Metabolism of the Heart

Abstract

The myocardial carbohydrate and non-esterified fatty acid metabolism in the human diabetic heart along with the effect of insulin and the changes of myocardial metabolism induced by the intravenous administration of glucocorticoid and epinephrine were studied by coronary sinus catheterization. In the diabetic heart, there was an unbalance of the supply and demand of oxygen, and disturbances in glucose, lactate, pyruvate and citrate metabolism. The insulin improved the disturbed glucose and citrate metabolism and in some cases the unbalance of the oxygen supply and demand in the myocardium. The myocardial fuel tended to shift from carbohydrate to lipid by the administration of glucocorticoid. The epinephrine also increased the myocardial lipid utilization and at the same time brought about slight myocardial hypoxia. It was proven in another experiment using C¹⁴ labelled substrates in the rat heart slice that the pentose phosphate pathway existed in a fairly large percentage and insulin, epinephrine and glucocorticoid influenced it. Part of the glucose extracted by the myocardium was stored as glycogen and lipid, though this might be temporary.