Metabolism of steroid and amino acid moieties of conjugated bile acids in man. V. Equations for the perturbed enterohepatic circulation and their application.

Equations previously developed to describe the enterohepatic circulation of the major biliary bile acids in man (Gastroenterology 67:887, 1974) were modified in order to predict the effect on biliary bile acid composition and pattern of amino acid conjugation after prototypic perturbations of the enterohepatic circulation in man. For the steroid moiety, the effects of bile acid feeding, increased recycling frequency, decreased intestinal conservation, and increased dehydroxylation were simulated. For the glycine or taurine moiety, the effect of increased deconjugation or preferential loss of one of the amino acid moieties was simulated. For the steroid moiety, the steady state biliary bile acid composition reflects the balance between input and conservation for each bile acid. Similarly, the distribution of bile acids between glycine and taurine conjugates reflects the balance between conjugation and conservation for each amino acid moiety. Because these values may vary widely and independently, analysis of biliary bile acid composition in terms of the steroid moiety or the glycine-taurine ratio per se cannot be used to infer the relative rates of input or conjugation.