Alteration of biliary ursodeoxycholic acid in guinea pig during early stages of cholestyramine feeding.

The effects of cholestyramine feeding on biliary ursodeoxycholic acid, fecal excretion of bile acids and neutral sterols on cholesterol 7 alpha-hydroxylase and hepatic HMG-CoA reductase were examined in the guinea pig. In the bile there was a 57% decrease in the concentration of ursodeoxycholic acid while an increase was observed in the concentration of chenodeoxycholic acid. Cholestyramine feeding for ten days resulted in a decrease in plasma cholesterol levels and an increase in both hepatic HMG-CoA reductase and cholesterol 7 alpha-hydroxylase activities. The fecal excretion of both bile acids and neutral sterols was significantly increased.