The uptake of doubly labeled chylomicrons by guinea pig mammary gland and liver

Abstract

The uptake of cholesterol-H3–palmitate-C14-chylomicrons by mammary tissue and liver has been examined. The cholesterol and glyceride components of chylomicrons were taken up at the same rate by both liver and mammary tissue, as demonstrated by the unchanged ratio of C14/H3 in the tissue lipids compared to the chylomicrons. However, following injection of glycerol-C14–palmitate-H3-chylomicrons, the H3/C14 ratio of the lipids of mammary tissue was much greater than the H3/C14 ratios of the injected chylomicrons, of the serum lipids, or of the liver lipids, indicating that appreciable hydrolysis of chylomicron glycerides occurred during their uptake by mammary glands. This is consistent with the hypothesis that lipoprotein lipase is involved in the uptake of chylomicron glyceride by mammary gland.