Effect of intraduodenal bile salt on pancreaticobiliary responses to bombesin and to cholecystokinin in humans

Bile salts modulate postprandial gallbladder emptying and pancreatic enzyme secretion, possibly by interfering with plasma cholecystokinin (CCK) respo nses. The regulatory role of bile salts in the absence of nutrients from th e gut is poorly understood. Therefore, we studied the effect of intraduoden al sodium chenodeoxycholate on bombesin (BBS)- or CCK-stimulated plasma CCK levels, plasma pancreatic polypeptide levels, gallbladder motility, and pa ncreatic enzyme secretion. In a crossover design, saline without or with ch enodeoxycholate was perfused intraduodenally for 3 hours in healthy volunte ers. During the last hour, either BBS (n = 9) or CCK (n = 10) was infused i ntravenously. Chenodeoxycholate inhibited BBS-stimulated gallbladder emptyi ng from 59% +/- 4% to 34% +/- 6% (P < .05) and intraduodenal bilirubin outp ut from 41 +/- 9 to 21 +/- 5 mu mol/h (P < .05), but it increased integrate d plasma CCK levels from 157 +/- 19 to 184 +/- 19 pmol/L . 60 min (P = .01) . Similarly chenodeoxycholate administration inhibited gallbladder emptying and bilirubin output in response to intravenous CCK. Chenodeoxycholate als o tended to reduce pancreatic polypeptide release and intraduodenal amylase output in response to intravenous BBS or CCK. It is concluded that intradu odenal chenodeoxycholate administration inhibits BBS- or CCK-stimulated gal lbladder emptying, probably by diminishing target organ sensitivity to circ ulating CCK.