Fig. 5. Acid-activated basolateral Na⁺/H⁺ exchange rates in differentiated C2PLKO.1 cells. C2PLKO.1 cells were acidified with the NH₃/NH₄⁺ pre-pulse technique. During the recovery phase, the basal side of the cell monolayer was perfused with Na⁺-containing buffer A, while the apical side with Na⁺-free buffer C. Inhibitors were added 5 minutes before pH_i recovery. (A) pH_i curve of basolateral pH_i recovery without inhibitors, (B) in the presence of 3 μM HOE642, (C) in the presence of 60 μM HOE642 in the basal perfusate in C2PLKO.1 cells. (D) comparisons of acid-activated basolateral Na⁺/H⁺ exchange rates without inhibition and after 3 μM HOE642 and 60 μM HOE642 treatments. The total basolateral Na⁺/H⁺ exchange rate of C2PLKO.1 cells was 0.310 ± 0.026 (△pH/min). 3 μM HOE642 reduced acid-activated basolateral Na⁺/H⁺ exchange rates to 0.063 ± 0.004 (△pH/min), and 60 μM HOE 642 to 0.056 ± 0.009 (△pH/min). (E) 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< 0.0001).