Regulation of lipid metabolism in the normal pig aorta Part 1. Influence of insulin and epinephrine on lipid synthesis from [U 14C] glucose

Abstract

The influence of insulin and epinephrine on the incorporation of uniformly labelled [ 14C]glucose into lipid of normal young pig aorta in vitro has been studied. Both the incorporation of [U 14C]glucose into aortic lipids, and the influence of insulin showed considerable variation. Over a concentration range from 0 to 10,000 μU/ml, insulin stimulated glucose incorporation into aortic total lipid. Stimulation was not constant, but appeared to be biphasic with a maximum at 100 μU/ml, a minimum at 1,000 μU/ml, followed by increasing stimulation to 10,000 μU/ml. At a physiological concentration of 25 μU/ml insulin significantly increased labelled glucose incorporation into aortic total lipid. This stimulation of incorporation was apparently not uniform for all aortic lipids, and was statistically significant only for the phosphatidyl choline fraction, although some influence on the other phospholipids cannot be excluded. Incorporation of label appeared to be increased in both the fatty acid and glycerol moieties of phosphatidyl choline. Insulin did not affect the uptake of [1— 14C] L-arabinose or [U 14C] sucrose by aortic tissue, suggesting that the increased glucose incorporation into lipid was not accompanied by an increased glucose uptake. Epinephrine, at 10 −8 M, had no effect on glucose incorporation into aortic lipid.