THE ROLE OF PLASMA FREE FATTY ACIDS IN THE ELEVATION OF PLASMA CHOLESTEROL AND PHOSPHOLIPIDS PRODUCED BY ADRENALINE

Abstract

SUMMARY: The effects of adrenaline, noradrenaline, corticotrophin (ACTH), cortisol and corticosterone on the levels of blood lipids have been studied in dogs and rats. Blood glucose, plasma free fatty acids (FFA) and corticosteroids were determined 4 hr. after injection. Plasma cholesterol, phospholipids and triglycerides were determined 24 hr. after the last of three daily treatments. In some experiments an oral glucose load was given at the same time as the hormones. In dogs plasma FFA were increased by adrenaline and noradrenaline, decreased by ACTH plus glucose and not affected by ACTH alone. Gradual rises in the lipoprotein levels of dogs were produced by any of the hormones given and followed acute rises in corticosteroid concentration regardless of the acute changes in plasma FFA. In rats plasma FFA were increased by adrenaline and ACTH, decreased by glucose and not affected by ACTH plus glucose. It was not possible to produce rises in lipoprotein by administering adrenaline or ACTH to rats. Exogenous corticosteroids produced increases in the cholesterol and phospholipid levels. The effects of corticosterone were potentiated by oral glucose but cortisol produced a full effect without extra glucose. The FFA responses to subcutaneous adrenaline in rats were reduced by adrenalectomy, but the increases in plasma FFA produced by intravenous infusion of adrenaline or ACTH were similar in adrenalectomized and intact rats. It was concluded that changes in lipoproteins are not causally related to increased mobilization of FFA but are dependent on increased adrenocortical hormone secretion in the presence of excess carbohydrate.