Effect of Intraduodenal Bile and Taurodeoxycholate on Exocrine Pancreatic Secretion and on Plasma Levels of Vasoactive Intestinal Polypeptide and Somatostatin in Man

Abstract

Summary: Intraduodenal (i.d.) application of bile or Nataurodeoxycholate (TDC) dose dependently enhances basal exocrine pancreatic secretion. The hydrokinetic effect is mediated at least in part by secretin. This study should show, whether vasoactive intestinal polypeptide (VIP), a partial agonist of secretin, may also be involved in the mediation of the hydrokinetic effect. Furthermore, plasma concentrations of somatostatin-like immunoreactivity (SLI) were measured in order to check whether this counterregulating hormone is also released by bile and TDC. Twenty investigations were carried out on 10 fasting healthy volunteers provided with a double-lumen Dreiling tube. Bile and TDC were intraduodenally applied in doses of 2-6 g and 200-600 mg, respectively, at 65-min intervals. Plasma samples were withdrawn at defined intervals for radioimmunological determination of VIP and SLI. Duodenal juice was collected in 10-min fractions and analyzed for volume, pH, bicarbonate, lipase, trypsin, and amylase. 1.d. application of bile or TDC dose dependently stimulated hydrokinetic and ecbolic pancreatic secretion. Bile exerted a slightly stronger effect than TDC. Pancreatic response was simultaneously accompanied by a significant increase of plasma VIP and SLI concentrations. The effect of bile on integrated plasma VIP and SLI concentrations seems to be dose dependent; the effect of TDC on integrated SLI, too. For the increase of integrated plasma VIP concentrations after TDC no doseresponse relation could be established. We conclude that VIP may be a further mediator of bile-induced volume and bicarbonate secretion. The release of plasma SLI indicates that inhibitory mechanisms concomitantly are triggered by i.d. bile and TDC, as already shown during digestion for the intestinal phase of pancreatic secretion. Key Words: Bile-Duodenum-Pancreatic secretionSomatostatin-Taurodeoxycholate-Vasoactive intestinal polypeptide.Intraduodenal (i.d.) application of bile or Nataurodeoxycholate (TDC) dose dependently enhances basal (1) and secretin-stimulated (2) hydrokinetic and ecbolic pancreatic secretion in man. The pancreatic response to i. d. bile (1,3,4) or bile salts (1,5,6) is accompanied by a release of secretin, the most important hormonal mediator of pancreatic volume and bicarbonate secretion (7-9).Vasoactive intestinal polypeptide (VIP) acts as a were not able to demonstrate a release of VIP in both portal and peripheral plasma after i.d. bile (3 g) in dogs. Therefore, one purpose of the present study was to investigate in man, whether VIP is dose dependently released by physiological loads of bile or TDC, a very effective bile salt with regard to pancreatic secretion (2).The intestinal phase of pancreatic secretion represents a net sum resulting from the responses to stimulatory and inhibitory mechanisms, as well (13). As we previously showed in man (l), i.d. ap- 209

Influence of Acute Exposure to High Altitude on Basal and Postprandial Plasma Levels of Gastroenteropancreatic Peptides

“…The assays for CCK [25], neurotensin [26], PP [27], and VIP [28] were established and evaluated in our laboratory of gastroenterology. The respective coefficients of intra-assay variation were 5.6, 9.8, 11.1, and 13.3%, and those of inter-assay variation were12.3, 14.0, 13.1, and 15.3%.…”

Defective Biliary Secretion during Total Parenteral Nutrition

“…They solubilize the lipolysis products of dietary triglyceride, as well as fatsoluble vitamins (22). Bile acids also induce release of somatostatin (23,24) , and they influence small intestinal motility (25). During the meal, bile acids return to the liver, induce bile flow and biliary lipid secretion as they traverse the hepatocyte, and are resecreted into bile.…”

Regulation of Pancreatic Secretion

“…In addition to secretin, infusion of bovine bile and bile acids in humans and dogs was shown to stimulate the release several hormones and neuropeptides such as CCK, neurotensin, VIP, gastric inhibitory peptide (GIP), PP, and somatostatin (34,42,274,276). Fluid and bicarbonate release was enhanced when elevated levels of VIP were present in the plasma, suggesting that bile activates peptidergic nerves resulting in pancreatic secretion.…”