Figure 6.

Slc4a11 disruption has little effect on pH_i regulation in SMG cells. Acinar and duct cells isolated from Slc4a11^+/+ and Slc4a11 ^−/− mouse SMGs were loaded with the pH‐sensitive dye BCECF and the intracellular pH (pH_i) change was monitored during the switch from pH 7.4–6 or from pH 7.4–9. All solutions were HCO₃ ⁻‐free (in the presence of 30 μmol/L EZA) to eliminate HCO₃ ⁻ transport pathways and contained 10 μmol/L EIPA to block Na⁺/H⁺ exchange. (A) The acidification rate of the acinar cells isolated from Slc4a11 ^−/− mice was compared to Slc4a11^+/+ mice (acidification rate (10⁻³/sec) of acinar cells = 0.81 ± 0.07 (n = 27, white circles) and 0.48 ± 0.07 (n = 31, black circles) for Slc4a11^+/+ and Slc4a11 ^−/−, respectively; P < 0.01). (B) The alkalization rate was comparable between acinar cells from Slc4a11^+/+ and Slc4a11 ^−/− mice (alkalization rate (10⁻³/sec) of acinar cells = 0.56 ± 0.10 (n = 22, white circles) and 0.60 ± 0.10 (n = 27, black circles) for Slc4a11^+/+ and Slc4a11 ^−/−, respectively; P > 0.05). (C) The acidification rate of the duct cells isolated from Slc4a11 ^−/− mice was compared to Slc4a11^+/+ mice [acidification rate (10⁻³/sec) of duct cells = 0.60 ± 0.06 (n = 24, white circles) and 0.36 ± 0.05 (n = 29, black circles) for Slc4a11^+/+ and Slc4a11 ^−/− mice, respectively; P < 0.01]. (D) The alkalization rate of duct cells from Slc4a11 ^−/− mice was identical to Slc4a11^+/+ mice [alkalization rate (10⁻³/sec) of duct cells = 0.70 ± 0.17 (n = 16, white circles) and 0.50 ± 0.12 (n = 26, black circles) for Slc4a11^+/+ and Slc4a11 ^−/−, respectively; P > 0.5]. Values are shown for individual SMGs along with the means ± SEM of glands isolated from 8 Slc4a11^+/+ and 9 Slc4a11 ^−/− mice. Intracellular pH is expressed as relative “F/F _o” values from the 490:440 ratio of the BCECF fluorescence measurements.