Intestinal absorption of bile alcohols.

The absorption of bile alcohols by rat small intestine was studied using in vivo and in vitro preparations. In bile duct cannulated rats, intraduodenal administered bile alcohols were certainly absorbed and excreted in the bile, although the absorption was not so efficient as for bile acids. The absorption during a 24 h period for free bile alcohol, bile alcohol 3-sulfate, and bile alcohol 3-glucuronide was 60%, 31%, and 30% of the dose, respectively, compared with 98% for taurocholate. In situ recirculation experiments demonstrated the linear relationship between perfusate concentration and intestinal absorption for unconjugated and 3-sulfated bile alcohols. Everted gut sacs of rat ileum actively transported a bile alcohol possessing a sulfuric acid ester group on the side chain. However, free bile alcohol, bile alcohol 3-sulfate, and bile alcohol 3-glucuronide were not transported. These results indicate that bile alcohols having no negative charge on the side chain are absorbed by passive diffusion and not by active transport.