Characterization of ion transport mechanisms involved in bombesin-stimulated biliary secretion in rat cholangiocytes

Background/Aims: Bombesin is a neuro:peptide which stimulates fluid and bicarbonate secretion from cholangiocytes by stimulating Cl-/HCO3- exchange, However, the underlying regulation anti interactions of ion transporters and channels mediating this bombesin-stimulated biliary secretion are not well characterized, The aim of the study was to characterize the ion transport processes involved in bombesin-stimulated secretion in polarized chol:angiocytes in comparison with those of secretin, Methods: Isolated bile duct units (IBDU) were prepared from normal rat liver, Biliary secretion induced by bombesin was measured by quantitative videomicroscopy in the presence and absence of inhibitors, Results: Bombesin-stimulated secretion was inhibited by H-2-DIDS, NPPB, BaCl2, TEA, and acetazolamide, However, in contrast to secretin, bombesin-stimulated secretion was not inhibited by disruption of microtubules. Conclusions: Bombesin-stimulated biliary secretion is dependent on anion exchangers, Cl- and K+ channels, and carbonic anhydrase but not on microtubules, Bombesin regulates secretion in cholangiocytes by different mechanisms from those established for secretin.