Metabolism of free fatty acids during perinatal life of lambs

Abstract

1.1. Studies of the mechanisms responsible for the rapid rise in the concentration of free fatty acids (FFA) in blood plasma after birth were done in newborn lambs.2.2. From changes in the specific radioactivity of free fatty acids of plasma during constant intravenous infusion of palmitate 1-C14 it was shown that the increase in plasma concentration of FFA after birth is the result of augmented mobilization of free fatty acids into the blood. This mobilization was reversed by blocking transmission at autonomic ganglia with hexamethonium.3.3. Intravenous injection of approximately 50 μg norepinephrine per kilogram body weight was required to increase FFA in blood plasma of newborn lambs; 2 μg per kilogram body weight was effective in ewes.4.4. Sensitivity to the effect of norepinephrine was not increased by fasting newborn lambs up to 40 hours, and increased sensitivity could not be demonstrated until the lambs were 8 weeks old.5.5. The results are compatible with the concept that increased activity of sympathetic nerves innervating adipose tissue is an important factor in the rapid mobilization of FFA into the blood after birth, and suggest that secretion of norepinephrine from the adrenal medulla is not involved.