The effect of glycine-conjugated bile acids on net transport and potential difference across isolated rat jejunum and ileum.

1. Five mM glycodeoxycholate and glycochenodeoxycholate inhibit net fluid transport across isolated rat jejunum and ileum; 5 mM glycocholate does not affect jejunal segments, but arrests fluid transport across ileal segments.2. Inhibition of fluid transport is accompanied by some diminution of mucosal glucose uptake, but translocation of glucose to the serosal surface of jejunal segments persists in the presence of dihydroxy conjugated bile acids.3. Inhibition of fluid transport is accompanied by a marked fall in the glucose-stimulated transmural electropotential difference, within 5 min of mucosal exposure to the bile acids.4. The lactate concentration gradient normally maintained across isolated intestine is abolished when fluid transport is inhibited by conjugated bile acids, even though lactate formation is not greatly reduced.5. These results suggest that inhibition of intestinal fluid transport is reproducible in vitro, and that the inhibition is not associated with increased permeability of the mucosa, but may be associated with altered permeability of the mucosal pole of the enterocyte.6. Although in vitro and in vivo effects of dihydroxy bile acids on fluid transport are similar, the assumption that the mode of action is likewise similar is not justified on present evidence.