Pigment gallstone formation and altered ion transport.

Feeding corn and alfalfa to young prairie dogs resulted in formation of gallstones composed of 45 percent cholesterol, 30 percent bile pigments, and 25 percent calcium bilirubinate in half of the animals. This diet also resulted in increased gallbladder bile concentrations of calcium, phospholipids, and cholesterol. Although the cholesterol saturation index was significantly increased compared with control subjects, it remained less than 1. In addition to the changes in biliary lipid composition, the corn and alfalfa-fed animals had significantly decreased transepithelial potential difference and short-circuit current when compared with control animals. These are changes in gallbladder mucosal function similar to those that have been reported in humans with gallstones. This model may therefore prove to be of great value in studying the pathogenesis of noncholesterol gallstones.