Evidence that vasoactive intestinal peptide induces ductular secretion of bile in humans.

The effect of intravenously administered vasoactive intestinal polypeptide on bile secretion was studied in 11 patients with complete biliary drainage. After infusion of vasoactive intestinal polypeptide, bile volume increased by 65%. In the 2 patients investigated, the output of bicarbonate increased by approximately 250% and the concentration by 50%-70%. Vasoactive intestinal polypeptide thus caused a bicarbonate-rich choleresis. The output of biliary lipids was not affected by infusion of vasoactive intestinal polypeptide, whereas the concentration decreased by approximately 40%. The canalicular bile flow, measured by the clearance of [14C]erythritol, was not affected by infusion of vasoactive intestinal polypeptide. The choleretic effect of vasoactive intestinal polypeptide thus seems to occur only at the ductular level. The ductular bile flow was calculated to be stimulated threefold to fourfold.