Secretin stimulates HCO3(-) and acetate efflux but not Na+/HCO3(-) uptake in rat pancreatic ducts.
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Pancreatic ducts secrete HCO3(-), but transport mechanisms are unresolved and possibly vary between species. Our aim was to study the intracellular pH (pHi) regulation and thus H+/HCO3- transport in rat pancreatic ducts. Of particular interest was the Na+/HCO3(-) cotransporter, thought to be important in HCO3(-) -transporting epithelia. pHi was measured with BCECF in freshly isolated intralobular ducts. A reduction in extracellular Na+ concentration or application of HOE 694 (1 microM) decreased pHi by 0.1 to 0.6 pH units, demonstrating Na+/H+ exchanger activity. A reduction in extracellular Cl- concentration or addition of H2DIDS (10 microM) increased pHi by 0.1 to 0.5 pH units, demonstrating Cl-/ HCO(3)- (OH ) exchanger activity. In experimental acidosis, extracellular HCO3(-)/CO2 buffer did not increase the rate of pHi recovery, indicating that provision of HCO3(-) by the Na+/HCO3(-) cotransporter was not apparent. Most importantly, Na+/HCO3(-) cotransport was not stimulated by secretin (1 nM). In contrast, in experimental alkalosis the pHi recovery was increased in HCO3(-)/CO2 buffer, possibly due to Na+/HCO3(-) cotransport in the efflux mode. Secretin (1 nM) and carbachol (1 microM) stimulated HCO3(-) efflux, which can account for the observed HCO3(-) concentrations in rat pancreatic juice. Acetate and HCO3(-) buffers were handled similarly, indicating similar transport mechanisms in pancreatic ducts.
Original language | English |
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Journal | Pflügers Archiv: European Journal of Physiology |
Volume | 441 |
Issue number | 6 |
Pages (from-to) | 761-71 |
Number of pages | 10 |
ISSN | 0031-6768 |
Publication status | Published - 2001 |
Bibliographical note
Keywords: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Acetates; Acidosis; Animals; Bicarbonates; Biological Transport; Carbachol; Cholinergic Agonists; Female; Hydrogen-Ion Concentration; Pancreatic Ducts; Quaternary Ammonium Compounds; Rats; Rats, Wistar; Secretin; Sodium; Sodium-Hydrogen Antiporter; Stimulation, Chemical
ID: 8569955