Evidence for apical Na+/H+ exchanger in bovine main pancreatic duct

The finding of a high PCO2 in basally secreted pancreatic juice of man and dog raises the hypothesis of proton secretion from ductal epithelial cells presumably through a Na+/H+ exchanger. To test this possibility, H+ luminal secretion and Na+ movements were measured in vitro on samples of bovine pa...

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Published in:Digestive diseases and sciences 1995-11, Vol.40 (11), p.2336-2340
Main Authors: MARTEAU, C, SILVIANI, V, DUCROC, R, CROTTE, C, GEROLAMI, A
Format: Article
Language:English
Subjects:
Amiloride - pharmacology
Animals
Biological and medical sciences
Cattle
Exocrine pancreas
Fundamental and applied biological sciences. Psychology
In Vitro Techniques
Nystatin - pharmacology
Ouabain - pharmacology
Pancreatic Ducts - metabolism
Sodium - metabolism
Sodium-Hydrogen Exchangers - antagonists & inhibitors
Sodium-Hydrogen Exchangers - metabolism
Vertebrates: digestive system
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Summary:The finding of a high PCO2 in basally secreted pancreatic juice of man and dog raises the hypothesis of proton secretion from ductal epithelial cells presumably through a Na+/H+ exchanger. To test this possibility, H+ luminal secretion and Na+ movements were measured in vitro on samples of bovine pancreatic ducts mounted in Ussing-type chambers. The rate of luminal acidification measured by the pH stat method, using bicarbonate-free media gassed with 100% O2, reached 2.75 muEq/cm2/hr. Proton secretion was blocked in the presence of 1 nM amiloride or in the absence of Na+ (replaced by choline) in the mucosal solution. Study of transepithelial 22Na fluxes in short-circuited tissue, bathed on both sides by control Ringer solution, gassed by 95% O2-5% CO2 demonstrated a net sodium transport from the mucosal to the interstitial side of the duct (net 22Na flux = 3.23 +/- 0.8 muEq/cm2/hr). This net sodium transport was electroneutral and blocked by mucosal amiloride (0.5-1 mM/liter) or by interstitial ouabain (1 mM/liter). These results are consistent with the existence of a Na+/H+ exchanger on the luminal side of the bovine main pancreatic duct.
ISSN:0163-2116
1573-2568
DOI:10.1007/BF02063234