Effect of Hypoglycemia on Plasma Renin Activity in Dogs

Insulin-induced hypoglycemia was associated with a statistically significant increase in the renin activity of arterial plasma in anesthetized dogs. This increase was accompanied by an increase in the rate of secretion and the peripheral arterial plasma level of epinephrine, and there was a statistically significant positive correlation between plasma levels of renin and epinephrine. The changes in renin and epinephrine levels were markedly reduced by unilateral adrenalectomy and denervation of the remaining adrenal, but not by bilateral renal denervation. Infusion of epinephrine at rates comparable to the secretion rate of this amine during hypoglycemia resulted in a smaller but statistically significant increase in plasma renin activity. Infusion of norepinephrine at this rate failed to increase plasma renin activity. Dopamine infusions increased renin secretion slightly but only at doses which cause a rise in peripheral arterial blood pressure. Hypoglycemia and epinephrine infusions were associated with a decline in plasma potassium, and a decrease in plasma potassium was also associated with an increase in plasma renin activity in insulin-treated dogs given glucose to prevent the blood sugar from falling. However, plasma renin activity also increased in hypoglycemic dogs in which potassium was infused intravenously. The data indicate that hypoglycemia is associated with increased renin secretion, and that the increase may be due in part to a decrease in plasma potassium, but that it is also due to increased secretion of epinephrine from the adrenal medulla.