The Influence of Adrenalectomy on the Metabolic Actions of Glucagon in the Fasted Rat1

The metabolic effects of daily injections of glucagon during a 5-day fast were investigated in adrenalectomized female rats maintained on either saline or hydrocortisone. As in the intact fasting rat, administration of glucagon to the adrenalectomized animal maintained on saline caused an increased urinary excretion of nitrogen, phosphorus and creatinine; a greater loss in body weight and decreased mass of liver and muscle tissues; and a fall in blood a-amino nitrogen. However, these changes were lesser in magnitude than the changes observed in the intact fasted rat. In contrast to its effects in the intact rat, administration of glucagon to the adrenalectomized animal maintained on saline did not depress liver glycogen but did elevate blood sugar and muscle glycogen. The metabolic responses to glucagon by adrenalectomized rats maintained on hydrocortisone were similar to those noted in the intact fasted animal. These studies suggest that the protein catabolic action of glucagon is not dependent on the presence of the adrenal cortex. They further suggest that the effects of glucagon on protein metabolism are an integral part of this hormone′s action.