Factors affecting the cholesterol dissolution ability of human bile.

Bile samples were obtained from 13 patients with cholesterol gallstones at laparotomy. Control bile samples were obtained from 15 patients with gastric cancer or gastric ulcer. One mixed stone was cut in half and serial thin sections, 10 micrometers in thickness, were prepared from the cut surface. The solubility of cholesterol in these gallstone sections after immersion in the bile samples was observed microscopically after 1, 3, 5 and 24 hr. Of 15 control bile samples, 9 showed a marked cholesterol dissolution after 1 hr, and 6 showed it after 3 and 5 hr. Three out of 13 bile samples from the patients with cholesterol stones dissolved the gallstone section after 1 hr, and 7 after 3 and 5 hr. The dissolution was not observed in the remaining 3 bile samples. Cholesterol and total bile acid concentrations of the control bile were significantly higher than those of the bile from the cholesterol gallstone patients (p less than 0.05 and p less than 0.02, respectively). Correlative studies of the composition of bile and its ability to dissolve cholesterol revealed that bile samples with a high total bile acid concentration possessed a higher dissolution ability, even when the ratios of total bile acid to cholesterol were almost the same in control and cholesterol gallstone bile. On the basis of these findings, it may be concluded that the solubility of cholesterol in bile cannot simply be explained in terms of relative concentrations of cholesterol, phospholipids and total bile acid, because the absolute concentration of total bile acid also plays a significant role for the dissolution ability.