REGULATION OF FECAL BILE-ACID EXCRETION IN MALE GOLDEN SYRIAN-HAMSTERS FED A CEREAL-BASED DIET WITH AND WITHOUT ADDED CHOLESTEROL

The objective of these studies was to investigate the comparative phys iology and regulation of bile acid metabolism in the male Golden Syria n hamster by measuring the rate of fecal bile acid excretion and bile acid pool size in animals fed a cereal-based diet either alone, or wit h added cholesterol or cholestyramine. In group-housed hamsters fed on ly the plain diet fecal bile acid excretion in animals at 6, 10, and 1 5 weeks of age averaged 11.0, 8.0, and 6.9 mu mol/d per 100 g body wei ght (bw), respectively, Pool size, measured by subtracting from the to tal amount of bile acid washed out over 12 hours of biliary diversion the amount of bile acid excreted in the stools over the same period, e qualled 17.8 mu mol/100 g bw in 15-week-old hamsters fed the plain die t, Hence, under basal conditions, these animals turned over about 38% of their bile acid pool daily, In hamsters fed a diet with 3% cholesty ramine for 18 days, fecal bile acid excretion averaged 20.6 mu mol/d p er 100 g bw, and the pool size contracted to 5.8 mu mol/100 g bw, In m atching animals fed a diet containing 0.12% cholesterol for 30 days, h epatic cholesterol levels increased from 1.9 +/- 0.1 to 12.6 +/- 0.7 m g/g, fecal bile acid excretion increased marginally from 5.8 to 8.0 mu mol/day per 100 g bw, while pool size was unchanged (16.6 mu mol/100 g bw), When the cholesterol content of the diet was raised to 1.0%, he patic cholesterol levels reached 66.5 +/- 2.6 mg/g, but bile acid excr etion remained at 8 mu mol/d per 100 g bw, These data define some of t he basal features of bile acid metabolism in the hamster, and substant iate the view that the marked cholesterolemic response of this species may relate partly to a limited ability to convert dietary cholesterol to bile acid.