Only free bile acid drives ileal absorption of taurocholate

We compared the intestinal absorption of monomeric taurocholate bound to albumin with the absorption of the free form. In the presence of albumin the apparent uptake coefficient is about three times greater than that in its absence. This result resembles the one reported previously for the liver. In the gut, however, this phenomenon is attributable to the diffusive resistance of an unstirred intervillous fluid layer, whereas in the liver this explanation has been excluded. We conclude that only free taurocholate engages the bile acid transport system in ileal mucosa, whereas in the liver bile acid uptake is driven by albumin-taurocholate complexes, as well as by free taurocholate.