Abstract
Summary
A comparative study of bile acid metabolism was made in the rat, mouse, hamster, and gerbil. Bile acid elimination was mainly via fecal excretion; less than 7% was excreted in the urine. Little or no bile acid side-chain oxidation took place in any of the species. A study of bile acid distribution in the rodent tissue showed that from 80 to 90% was present in the small intestine plus gall bladder. The cecum was another site which contained considerable quantities of bile acids. The chief pool bile acid in each case was cholic acid. Chenodeoxycholic acid was present in significant amounts in rat and hamster, and in trace amounts in mouse and gerbil bile. Cholic acid half-lives (days) were: rat, 3.5; mouse, 5.0; gerbil, 2.3; and hamster, 1.0. Chenodeoxycholic half-lives (days) were: rat, 2.0; mouse, 2.5; gerbil, 1.3; and hamster, 1.8. The rat had the largest bile acid pool (27.2 mg); the mouse (5.6 mg) and gerbil (7.12 mg) intermediate amounts; and the hamster the smallest pool (2.3 mg). The relationship between bile acid synthesis rates and the rate of accumulation of tissue cholesterol after feeding cholesterol-supplemented diets was discussed. Positive correlations were noted but further studies are necessary to define the relative importance of this factor in maintaining cholesterol homeostasis in the various rodents.
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