The metabolic role of endogenous catecholamines in acute myocardial infarction: effects of reserpinization and of infused noradrenaline.

A significant decrease of the noradrenaline content of the ischemic as well as non-ischemic parts of the myocardium was found in rats after ligation of the left coronary artery. The eventual role of released noradrenaline in the anaerobic metabolism of the heart was investigated. A highly significant decrease of ATP and glycogen was obtained in the ischemic myocardium 10 min after coronary ligation whereas glucose-6-phosphate (g-6-p) was significantly increased. Catecholamine depletion by reserpine pretreatment did not reduce the loss of ATP, although the hearts had broken down rather higher amounts of glycogen. Glycolytic energy production was obviously inhibited, as the accumulation of g-6-p was significantly greater than in non-reserpinized animals. However when a high breakdown of glycogen was induced by noradrenaline infusion into coronary ligated animals, the g-6-p levels were no higher than those in untreated coronary-ligated rats. The results suggest that the ischemic breakdown of glycogen is independent of endogenous noradrenaline. The metabolic conversion of g-6-p, however, may need sufficient catecholaminergic stimulation to become fully activated.