Fig. 3
Evaluation of the contribution of carbonic anhydrases and CFTR Cl− channels to forskolin + IBMX-induced pHi changes. a–c Relationships between the averaged rates of pHi decreases (−ΔpH per 10 s) versus the corresponding, averaged pHi during the pHi-decreasing phase by 10 μM forskolin + 100 μM IBMX (F+I) stimulation in the presence of 5(N,N)-dimethyl amiloride (DMA; 20 μM), and its combination with CFTR inhibitor 172 (CFTR172; 10 μM) or methazolamide (Met; 1 mM). The averaged rates of pHi decreases were plotted at 10 s intervals as the pHi was decreased by F+I stimulation with the starting point indicated as F+I added. Data shown are mean ± SE (n = 6, 7, and 6, respectively). d The rates of F+I-induced decreases in pHi (−ΔpH per 10 s) at pHi of 7.27 in the presence of DMA. Simultaneous addition of CFTR172 with DMA reduced the rate, and the addition of methazolamide reduced the rate more effectively (n = 6, 7, and 6, respectively). The rate at pHi 7.27 was obtained by using linear interpolation between two data points of the means, as indicated by an arrow, in (a–c) of each condition