The relationship of cholecystectomy and taurocholic acid feeding to bile composition and hepatocyte function in prairie dogs.

The prairie dog was used as a model for human gallstone formation. Stones formed in the gallbladder of all animals on a lithogenic diet. Hepatic bile was nonlithogenic, whereas gallbladder bile promoted cholesterol precipitation. Addition of taurocholate to the diet reduced the number of stones and lithogenicity. Cholecystectomy resulted in an increased bile flow and reduced secretion of cholesterol in the animals on a high cholesterol diet. Reduction of cholesterol and bile acid synthesis by negative feedback was demonstrated in isolated hepatocyte culture. The shift of bile salt production to chenodeoxycholates on a high cholesterol intake was demonstrated both in vivo and in vitro. A theory of gallstone formation is presented which hypothesizes a defect in hepatocyte storage of cholesterol rather than bile acid synthesis as the primary effect, relegating the problems to one of a disease of lipid metabolism.