THE ESSENTIAL ROLE OF THE ADRENAL CORTEX IN THE RESPONSE OF PLASMA FREE FATTY ACIDS, CHOLES-TEROL, AND PHOSPHOLIPIDS TO EPINEPHRINE INJECTION *

Abstract

Intravenous injection of aqueous epinephrine (20-25 [mu]g/kg) into normal dogs caused prompt elevation of plasma free fatty acids (FFA), maximal at 5-10 min. and returning to normal at 20 min. After adrenalectomy or hypophysectomy the same dogs given the same doses of epinephrine showed no rise in FFA. Treatment with cortisone restored FFA responses to normal in these operated animals. Subcutaneous injection of epinephrine in oil (0.6 mg/kg) caused a rise of FFA maximal at 2-3 hr., returning to normal at 6 hr. Cholesterol and phospholipid levels in plasma were normal at 6 hr. but elevated at 24 hr. Three daily injections of epinephrine in oil raised cholesterol levels 29-61% and phospholipid levels 22-46% over control levels. Changes in triglyceride were not consistent. After adrenalectomy or after hypophysectomy the FFA, cholesterol and phospholipid responses to epinephrine in oil were abolished or reduced to very low levels. Treatment of adrenalectomized dogs with cortisone restored all responses to normal. Treatment with ACTH partially restored FFA response and completely restored cholesterol and phospholipid response in hypophysectomized animals. Cortisone fully restored FFA response in hypophysectomized dogs. Cortisone treatment of normal dogs potentiated both FFA and cholesterol and phospholipid responses to epinephrine. It was concluded that mobilization of FFA and of lipoproteins by epinephrine is dependent upon normal adrenal function, particularly on the simultaneous availability of cortisone-like steroids.