Fig. 9. Acid-activated apical Na⁺/H⁺ exchange rates in differentiated C2NHE2KD cells. The experimental design, solutions and inhibitors were the same as in Fig. 6. (A) pH_i-recovery curve without inhibitors, (B) in the presence of 60 μM HOE642, (C) in the presence of 1 μM tenapanor, (D) in the presence of 60 μM HOE642 and 1 μM tenapanor during apical Na⁺ re-addition in C2NHE2KD cells. (E) Comparisons of acid-activated apical Na⁺/H⁺ exchange rates under control, 60 μM HOE642, 1 μM tenapanor, and 60 μM HOE642 plus 1 μM tenapanor. The total apical Na⁺/H⁺ exchange rate of C2NHE2KD cells was 0.050 ± 0.005 (△pH/min). 60 μM HOE642 reduced acid-activated apical Na⁺/H⁺ exchange rate to 0.031 ±0.004 (△pH/min), 1 μM tenapanor to 0.036 ± 0.003 (△pH/min) and 60 μM HOE642 plus 1μM tenapanor to 0.015 ± 0.004 (△pH/min). (F) Comparisons of initial pH_i at the beginning of acid-induced pH_i recovery among different groups. (n=5, mean ± SEM, one-way ANOVA with Tukey's multiple comparison tests, *p< 0.05, **p< 0.001, ***p< 0.0001).