Exocrine pancreatic secretion and plasma levels of cholecystokinin, pancreatic polypeptide, and somatostatin after single and combined intraduodenal application of different bile salts in man

Bile salts are intraduodenal stimulants of basal pancreatic secretion. This study aims to show whether the three main bile salts of human bile differ in their action on pancreatic secretion, and whether they enhance or inhibit each other after combined use. Furthermore, the effect on gastroenteropancreatic peptide release is evaluated. Twelve subjects were provided with a gastroduodenal double-lumen tube. Equimolar doses (0.6 mmol) of taurocholate (322 mg), taurodeoxycholate (313 mg), and a combination of both stimuli were given intraduodenally. Another 12 subjects received taurochenodeoxycholate (313 mg) instead of taurocholate. Volume, bicarbonate, trypsin, and lipase were determined in duodenal aspirates. Cholecystokinin, pancreatic polypeptide, and somatostatin were measured radioimmunologically in plasma samples. All bile salts and combinations exerted a significant hydrokinetic and ecbolic effect. The hydrokinetic response of the combined stimuli was significantly higher as compared with taurocholate and taurochenodeoxycholate, respectively. As far as concerns the ecbolic response, the difference was significant only for trypsin output as compared with taurochenodeoxycholate. Plasma cholecystokinin rose significantly only after the combined stimuli. Pancreatic polypeptide and somatostatin increased significantly after all stimuli, except pancreatic polypeptide after taurocholate. Combined use enhances the hydrokinetic and ecbolic effects of single bile salts. Cholecystokinin may, hereby, be involved as a mediator of the ecbolic effect. Pancreatic polypeptide release indicates cholinergic mechanisms as further mediators. As demonstrated by somatostatin release, counter-regulatory mechanisms are also triggered by intraduodenal bile salts.