Role of CFTR and anion exchanger in bicarbonate fluxes in C127 cell lines.

C127 cell lines transfected with wtCFTR, delta F508CFTR or vector were employed to determine HCO3- fluxes in the presence or absence of functional CFTR, using the pH-sensitive dye BCECF. Both cytosolic alkalinization and acidification were due to activity of anion exchanger and were similar in the three cell lines, indicating that expression of CFTR did not influence anion exchanger activity. In C127wt cells only, cAMP elevating agents significantly stimulated HCO3- fluxes, insensitive to the inhibitor of anion exchanger 4,4'-diisothiocyanate dihydrostilbene-2,2'-disulfonic acid, suggesting that activated CFTR directly mediates both HCO3- influx and efflux and therefore can contribute to intracellular and extracellular pH regulation.