Effect of adrenal denervation on the glucose, insulin, and glucagon responses to exercise in sheep

Previous studies suggest that adrenal catecholamines mediate, in part, the glucose and pancreatic hormonal responses to exercise in sheep. This was examined in sheep whose adrenals were denervated to prevent stress-induced changes in catecholamine secretion. The innervation to the right adrenal gland was severed and the left adrenal was removed. Adrenal denervation was associated with a reduction in exercise-induced hyperglycemia and impairment, as measured by [2-3H]glucose, of the increase in glucose appearance during the first 10 min of exercise and increased metabolic clearance rate of glucose after 20 min of exercise. Insulin concentrations were significantly higher during exercise after adrenal denervation than in the controls. Adrenal denervation did not alter the rise in glucagon due to exercise. These effects are consistent with adrenomedullary hormonal stimulation of hepatic and muscular glycogenolysis, either directly or indirectly through the regulation of insulin secretion during exercise in sheep.