Fig. 1.

Cl⁻-dependent HCO₃⁻ and fluid secretion in interlobular pancreatic ducts isolated from wild-type and Slc26a6^−/− mice. Sealed, isolated ducts from wild-type and Slc26a6^−/− mice were filled with Cl⁻-rich (149 mM) HCO₃⁻-free HEPES-buffered solution containing 2′7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF)-dextran (20 μM). The bath was first perfused with the same HCO₃⁻-free solution, and then the bath solution was switched to the standard HCO₃⁻-buffered solution containing 25 mM HCO₃⁻ and 124 mM Cl⁻ as indicated. Cells were stimulated with forskolin (1 μM) throughout the experiments. Luminal pH and luminal volume were measured simultaneously. A and B: changes in luminal pH in 3 representative ducts isolated from wild-type (A) and Slc26a6^−/− (B) mice respectively. C and D: changes in fluid secretory rate in the same wild-type (C) and Slc26a6^−/− (D) ducts. Negative values indicate fluid absorption. E and F: changes in calculated fluxes of Cl⁻ (red) and HCO₃⁻ (black) in the same wild-type (E) and Slc26a6^−/− (F) ducts. Positive and negative values indicate secretory and absorptive fluxes, respectively. G and H: plot of cumulative fluxes of Cl⁻ and HCO₃⁻ during the first 5 min after bath application of HCO₃⁻ in wild-type (G, n = 7) and Slc26a6^−/− ducts (H, n = 11). I and J: final values of luminal pH (I) and steady-state fluid secretory rate (J) in wild-type and Slc26a6^−/− ducts. Data are means ± SE. *P < 0.05, significant difference.