Abstract

Isotopic bile salt studies have been performed in 13 cholecystectomy patients and 10 matched controls using labelled taurocholate and deoxycholic acid. Cholecystectomy subjects have reduced pools of both primary bile salts, cholate and chenodeoxycholate, while the deoxycholate pool remains normal in size. As a result of these changes, the total bile salt pool is reduced to almost half its normal size and deoxycholate becomes the predominant bile salt. The half-life of taurocholate is reduced but, because its pool size is diminished, the daily synthesis of taurocholate remains normal. There is accelerated transfer of ¹⁴C from taurocholate-24-¹⁴C to its metabolites in bile, especially deoxycholate conjugates. In four subjects studied pre- and postoperatively similar changes occurred in all the above parameters.

All these data can be explained by the fact that the bile salt pool circulates during fasting as well as during digestion. The consequences of this are (1) increased exposure of bile salts to intestinal bacteria and hence increased bacterial degradation; (2) continuous passage of the bile salt pool through the liver, and therefore continuous and presumably enhanced feedback inhibition of hepatic bile salt synthesis.

The reservoir function of the gallbladder influences the size, kinetics, metabolism, and composition of the bile salt pool. We suggest that no study of bile salt metabolism is complete without some assessment of gallbladder status.