Characterization of ion transport mechanisms involved in bombesin-stimulated biliary secretion in rat cholangiocytes.
OBJECTIVE
Bombesin is a neuropeptide which stimulates fluid and bicarbonate secretion from cholangiocytes by stimulating Cl-/HCO3- exchange. However, the underlying regulation and 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 cholangiocytes 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 video-microscopy in the presence and absence of inhibitors.


RESULTS
Bombesin-stimulated secretion was inhibited by H2-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.
Cho
W K
WK
Division of Gastroenterology/Hepatology, Indiana University School of Medicine, Indianapolis 46202, USA. wkcho@iupui.edu
Boyer
J L
JL
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000086:Acetazolamide / Q000494:pharmacology; D000818:Animals; D017609:Barium Compounds / Q000494:pharmacology; D001646:Bile / Q000378:metabolism*; D001652:Bile Ducts / Q000166:cytology / Q000378:metabolism*; D001839:Bombesin / Q000494:pharmacology*; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology; D018118:Chloride Channels / Q000187:drug effects; D002712:Chlorides / Q000494:pharmacology; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects / Q000502:physiology*; D008297:Male; D018715:Microscopy, Video; D009579:Nitrobenzoates / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D019789:Tetraethylammonium / Q000494:pharmacology
D017609:Barium Compounds; D002257:Carbonic Anhydrase Inhibitors; D018118:Chloride Channels; D002712:Chlorides; D009579:Nitrobenzoates; D015221:Potassium Channels; C024986:barium chloride; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D019789:Tetraethylammonium; D000086:Acetazolamide; D001839:Bombesin; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid