Intracellular pH in rat pancreatic ducts.
In order to study the mechanism of H+ and HCO3- transport in a HCO3- secreting epithelium, pancreatic ducts, we have measured the intracellular pH (pHi) in this tissue using the pH sensitive probe BCECF. We found that exposures of ducts to solutions containing acetate/acetic acid or NH4+/NH3 buffers (20 mmol/l) led to pHi changes in accordance with entry of lipid-soluble forms of the buffers, followed by back-regulation of pHi by duct cells. In another type of experiment, changes in extracellular pH of solutions containing HEPES or HCO3-/CO2 buffers led to significant changes in pHi that did not seem to be back-regulated efficiently by duct cells. The sensitivity of pHi to the inhibitor HOE 694 and to changes in Na+ gradients, indicate that the Na+/H+ exchanger is present in this epithelium. Similarly, the sensitivity to Cl- and HCO3- gradients indicated the presence of the Cl-/HCO3- exchanger. Under some conditions, these exchangers can be invoked to regulate cell pH.
Novak
I
I
August Krogh Institute, University of Copenhagen, Denmark. inovak@aki.ku.dk
Hug
M
M
Greger
R
R
D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010183:Pancreatic Ducts / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism
D001639:Bicarbonates; D002712:Chlorides; D017923:Sodium-Hydrogen Exchangers