Secretin stimulates bile ductules to secrete both H+ and HCO3--ions

Secretin-dependent ductular HCO3- secretion into bile may involve secretion of H+ to interstitial fluid and HCO3- to bile by the ductular epithelium. To determine whether secretin causes bile ductules to secrete H+, we have examined the effect of secretin on the elimination of an intracellular acid...

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Bibliographic Details
Published in:Acta physiologica Scandinavica 1992-11, Vol.146 (3), p.369-376
Main Authors: VILLANGER, O, VEEL, T, HOLTHE, M. R, CRAGOE, E. J, RÆDER, M. G
Format: Article
Language:English
Subjects:
Amiloride - analogs & derivatives
Amiloride - pharmacology
Animals
Bicarbonates - metabolism
Bile Ducts - drug effects
Bile Ducts - metabolism
Biological and medical sciences
Cytoplasm - drug effects
Cytoplasm - metabolism
Epithelium - drug effects
Epithelium - metabolism
Fundamental and applied biological sciences. Psychology
Hydrogen - metabolism
Hydrogen-Ion Concentration
In Vitro Techniques
Ion Exchange
Liver - drug effects
Liver - metabolism
Liver. Bile. Biliary tracts
Secretin - pharmacology
Stimulation, Chemical
Swine
Vertebrates: digestive system
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Summary:Secretin-dependent ductular HCO3- secretion into bile may involve secretion of H+ to interstitial fluid and HCO3- to bile by the ductular epithelium. To determine whether secretin causes bile ductules to secrete H+, we have examined the effect of secretin on the elimination of an intracellular acid load from bile ductular epithelium during pharmacological blockade of Na(+)-H+ exchange and in the absence of HCO3-. Microdissected bile ductules from pigs were suspended in HCO3- free HEPES buffer and loaded with acid using an NH4Cl prepulse technique. Intracellular pH was measured using dual-wavelength excitation of BCECF fluorescence. Na(+)-H+ exchange was defined as a Na(+)-dependent and amiloride- and 5-(N,N-hexamethylene)-amiloride-sensitive efflux of H(+)-ions following acid loading. We found that secretin stimulated ductular H+ secretion independent of Na(+)-H+ exchange. Blockade of Na(+)-H+ exchange by hexamethylene-amiloride did not affect secretin-dependent ductular HCO3- choleresis in vivo. We conclude that secretin stimulates bile ductules to secrete H(+)-ions to interstitial fluid as well as HCO3- ions to bile by a mechanism independent of Na(+)-H+ exchange.
ISSN:0001-6772
1365-201X
DOI:10.1111/j.1748-1716.1992.tb09431.x