Secretin causes H+/HCO3− secretion from pig pancreatic ductules by vacuolar-type H+-adenosine triphosphatase
| Autor: | Morten G. Ræder, Olaug Villanger, T. Veel |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Male
medicine.medical_specialty Sodium-Hydrogen Exchangers Swine Bicarbonate Intracellular pH Buffers digestive system Ammonium Chloride Secretin Amiloride chemistry.chemical_compound Chlorides Internal medicine medicine Animals HEPES Hepatology Sodium Pancreatic Ducts Gastroenterology Bafilomycin Hydrogen-Ion Concentration Anti-Bacterial Agents Bicarbonates Proton-Translocating ATPases Endocrinology chemistry Pancreatic juice Female Triphosphatase Macrolides Cotransporter Hydrogen |
| Zdroj: | Gastroenterology. 108:850-859 |
| ISSN: | 0016-5085 |
| DOI: | 10.1016/0016-5085(95)90460-3 |
| Popis: | Background/Aims: Secretin stimulates pancreatic ductules to secrete HCO3− into pancreatic juice and H+ into interstitial fluid. The aim of the present study was first to examine whether ductular H+ secretion is inhibited by micromolar concentrations of bafilomycin A1, which blocks vacuolar H+-adenosine triphosphatase by specific action, and secondly to test for evidence of ductular Na+/HCO3− cotransport. Methods: Ductular H+ secretion was estimated from the rate of intracellular pH recovery after acid-loading (24 mmol/L NH4Cl) microdissected pancreatic ductules from pig, mounted in a flow-through perfusion chamber on the stage of a fluorescent microscope. Intracellular pH was measured using the fluorescent pH indicator 2′7′-bis (carboxyethyl)-5,6-carboxyfluorescein and dual-wavelength excitation of fluorescence. The ducts were superfused with either HCO3−-free HEPES-containing buffers or HCO3−-containing buffers. Results: Secretin (10−8 mol/L) induced a net H+ secretion of 1.87 ± 0.23 μmol · mL cell vol−1 · min−1 that was blocked by 10−6 mol/L bafilomycin A1 and was unaffected by Na+ substitution with choline using HEPES superfusion buffers. Secretin-stimulated ductules superfused with bicarbonate-containing, Cl−-free buffers showed Na+-dependent and 4,4′-diisothiocyanostilbene-2, 2′-disulfonic acid-inhibitable alkalinization of intracellular pH. Conclusions: Secretin causes H+/HCO3− secretion from pancreatic ductules by a mechanism involving vacuolar-type H+-adenosine phosphatase. Pancreatic ductules also show Na+/HCO3− cotransport, which may account for a small fraction of secreted bicarbonate. |
| Databáze: | OpenAIRE |
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