Inhibition of adrenal secretion of epinephrine during infusion of catecholamines

¹ Department of Pharmacology, West Virginia University Medical Center, Morgantown, West Virginia

The effect of intravenous infusion of epinephrine or norepinephrine on the secretion of epinephrine by the adrenal was studied in dogs. The epinephrine content of adrenal venous blood was assayed on the rat uterus, automatically stimulated. The infusion of epinephrine or norepinephrine at a rate which produced an increase in blood pressure inhibited the output of epinephrine by the adrenal. If the rate of infusion of catecholamines was too slow to increase the blood pressure, or if the increase in blood pressure was prevented by a pressure compensator, secretion of epinephrine was not inhibited. A good correlation exists between the per cent decrease in epinephrine secretion and the per cent increase in blood pressure produced by infusion of catecholamines. It appears that the inhibition of epinephrine secretion during infusion of catecholamines is produced reflexly by the induced increase in blood pressure. In two experiments the aortic epinephrine concentration exceeded the adrenal venous epinephrine concentration during infusion of epinephrine, suggesting an uptake of epinephrine by the adrenal gland.