The effects of lithogenic bile on gallbladder epithelium.

Prairie dogs were fed a 1.2% cholesterol diet for up to 24 weeks to evaluate the effects of lithogenic bile on the mucosa of the gallbladder. There was a progressive increase in the lithogenic index of the gallbladder bile (1.44 +/- 0.15 at 4 weeks, p less than 0.05). Fifty-five of 70 animals developed gallstones between the second and fourth week. Increasing stone burden was associated with a 27% (p less than 0.05) decrease in the electrical resistance of the epithelium and a 60% (p less than 0.05) decrease in net sodium transport when measured isotopically in an Ussing chamber (3 weeks). After 4 months, seven of ten animals developed inflammatory mucosal polyps characterized by a heavy infiltration of plasma cells into an expanded matrix. Cellular infiltration began as early as 2 weeks. These changes occurred without alterations in the ultrastructural appearance of the epithelium.