Figure 2

Intracellular pH measurement using ammonium pulse protocol (see methods). Perfusion of FRT WT-CFTR and F508del-CFTR cells with 30 mM of NH⁺₄ causes the augment of the pH_I followed by rapid acidification when NH⁺₄ is removed. When bicarbonate was perfused an alkalinization was observed upon the 100 µM pCPT-CAMP stimulation in FRT WT-CFTR (A); FRT WT-CFTR without pCPT-CAMP stimulation or with Cl⁻ in place of HCO₃⁻ was used as control (B,C). FRT p.F508del-CFTR cells not incubated with correctors do not elicit any pH_i variation and consequent bicarbonate transport (D), while incubation with VX809, VX661, Corr4a and the combination of VX809 and Corr4a, gives rise to an HCO₃⁻ influx (E–H). The panel I show the summary of bicarbonate influx of p.F508del-CFTR not incubated (red); incubated with VX809 (orange), VX661 (gray), Corr4a (blue) and the combination (green) respectively. Data are means ± SEM. The number of experiments for each condition was between 8 and 12.