Cholesterol gallstones and biliary lipid metabolism in the primate.

A primate model for the study of cholesterol gallstones is described. Bile became supersaturated with cholesterol in 7 female adult baboons with exteriorized enterohepatic circulations during 0.2 g per kg per day of cholestyramine treatment. Cholestyramine decreased bile acid pool size (1.38 +/- 0.7 to 0.45 +/- 0.02 mmole, P less than 0.001) and secretion rate (12.7 +/- 0.9 to 5.6 +/- 0.5 mmoles per 24 hr) while cholesterol secretion remained unaltered. Although biliary lipid and bile acid composition were similarly affected by treatment in both cholecystectomized and intact animals, cholesterol stones formed only in the latter. Thus metabolic alterations in biliary lipid metabolism as well as the presence of the gallbladder were necessary for stone formation.