Transfer of Radioactivity of Cholesterol-7α-³H to Fatty Acids of Tissue Lipids in vivo

Abstract

WHEN randomly labelled cholesterol (either with carbon-14 or tritium) was fed to rats, a small but appreciable amount of the administered radioactivity could be recovered in the carcass fatty acids¹. In both cases it was assumed that the label was due to incorporation of the carbon atoms of the isopropyl group of the cholesterol side-chain into the isolated fatty acids. In the course of recent experiments involving cholesterol metabolism in baboons we administered cholesterol-6α-³H (5 mc.) to a male baboon (18 kg) which was killed 3 days later. The lipids of a number of tissues (liver, spleen, kidney, lung, adrenal) were extracted with chloroform–methanol 2: 1 (ref. 2), separated by chromatography on silicic acid³ and assayed for radioactivity by liquid scintillation spectrometry.