Characterization of H+ and HCO3- transporters in CFPAC-1 human pancreatic duct cells

Figure 10 H⁺ and HCO₃^– transport mechanisms in CFPAC-1 human pancreatic duct cells. The basolateral membrane expresses Na⁺/HCO₃^– co-transporters, Na⁺/H⁺ exchangers and Cl^–/HCO₃^– exchangers plus an unidentified Na⁺-independent HCO₃^– entry pathway. These transporters facilitate the rapid flux of HCO₃^– ions into the cell. K⁺ channels are also likely to be expressed on the basolateral membrane because altering extracellular K⁺ concentration affects HCO₃^– influx. The apical membrane expresses Na⁺/H⁺ exchangers, but not CFTR and Cl^–/HCO₃^– exchangers found in normal pancreatic duct cells. The apical membrane is an effective barrier to HCO₃^– influx from the lumen, but is freely permeable to CO₂. CA: Carbonic anhydrase.