The role of the adrenal medulla in the contol of gluconeogenesis in the rat.

The role of adrenal catecholamines in the control of gluconeogenesis was determined in adrenal-demedullated (AD) and sham-operated (SO) rats. In animals which were fasted, plasma levels of glucose, lactic acid, glycerol, alanine as well as liver or skeletal muscle glycogen, and incorporation of lactic acid-14C into glucose were not significantly different between AD and SO rats. During exercise (forced running), SO rats were found to have significantly higher plasma glucose levels, lower skeletal muscle glycogen levels, and greater incorporation of lactic acid-14C into glucose that AD rats. No significant differences in plasma levels of lactic acid, glycerol, alanine, or liver glycogen were detected in the animals which were exercised. During a combined regimen of fasting and exercise, SO rats exhibited higher plasms glucose levels and significantly greater incorporation of lactic acid-14C into glucose than did AD rats. Epinephrine administration produce quantitatively similar effects on blood glucose levels and on incorporation of lactic acid-14C into glucose in fasted, exercised AD and SO rats. Glucose utilization, as measured by the disapperance of glucose-14C from the plasma of fasted, exercised rats, was not altered by adrenal demedullation. It is concluded that, under certain conditions, adrenal medullary catecholamines play a significant role in the control of gluconeogenesis in the rat, probably through an effect on the glucose synthesizing enzyme systems of the liver.