Production and Excretion of Cholesterol in Mammals

Publisher Website
Google Scholar
Abstract
Biliary cholesterol excretion averaged 1.8 mg. per rat per day after diets low, normal, or high in cholesterol (15 rats); parenterally administered hypercholesteremic serum (20 mg. of cholesterol to each of 12 rats); plasmapheresis resulting in plasma cholesterol lowering by 66% (5 rats); or hypercholesteremia consequent upon bile duct ligation, with subsequent conversion of the bile duct tie to a fistula (8 rats). Although each animal with exptl. altered plasma cholesterol restored normal levels during the 24 hrs. of bile collection, the bile cholesterol output was invariant, independent of the exptl. procedure, and the same as the output of normal control animals. The rate of bile cholesterol excretion diminished in corresponding ratio when the rate of hepatic cholesterol synthesis was diminished by: (1) 60% subtotal hepatectomy, 0.7 mg. cholesterol/rat/day (10 rats), (2) admn. of CCI4,0.8 mg. cholesterol/rat/day (8 female rats), or (3) production of hypothyroidism by thiouracil, 0.8 mg. cholesterol/ rat/day (9 rats). High rate of hepatic synthesis as in 17 immature rats was associated with high daily rate of excretion of cholesterol in bile (avg. 2.7 mg./rat/day). The highest rate of biliary excretion avg. 8 mg./rat/day in a group of 6 rats fed thyroid substance. Apparently biliary cholesterol represents a fixed fraction of the cholesterol synthesized by the liver indicates the hepatic rate of cholesterol synthesis.