Abstract
Summary
Cholesterol-C14 and cholesterol-H3 were fed to rabbits for 1 week and cholesterol was isolated from aortae, livers, small intestines, adrenals, kidneys, brains and blood. Isolated material from all tissues had a lower count than the material fed. It was surprising that cholesterol-H3 counts were always comparatively lower than cholesterol-C14 counts. This discrepancy may be explained by a peripheral oxidation of the cholesterol-H3 molecule, in which it loses radioactive hydrogen and therefore radioactivity. This peripheral oxidation is apparently mainly operative in blood. If after feeding of radioactive material non-radioactive cholesterol is fed for 7 or 11 weeks, radioactivity in both types of experiments is reduced to a small fraction of original values. From these data one can calculate that about 0.03 mg cholesterol are laid down in the aorta/animal/day/g of wet tissue, a very small part of the 900 mg fed/day/animal. The experiments show that there is a continuous exchange of radioactive cholesterol between tissues and blood in which even the plaques, formed in the aortae, must take part.
The help of Erszebet Joachim, Eva Moring and Deirdre McLeod is gratefully acknowledged.
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