(A) Effects of 10^–4 M ACZ on Cl^– transepithelial transport in CCDs isolated from Ncc^–/– mice. CCDs were isolated from Ncc^–/– mice and bathed and perfused with CO₂/HCO₃^–-containing solutions. Statistical significance was assessed by 2-tailed Student’s unpaired t test. n = 5 in each group; *P < 0.001 versus control. (B) Effects of luminal 10^–4 M ACZ on pendrin activity in isolated CCDs. Tubules were isolated from wild-type mice. Pendrin activity was assessed by measuring changes in pH_i when Cl^– was removed and then readded from the perfusate. Both bath and perfusate solutions contained 25 mM HCO₃^– and were sodium-free. Traces represent the average of recordings from independent tubules. n = 4–5 independent tubules by group. Mean starting pH_i values were 6.91 ± 0.03 and 6.72 ± 0.05, in the absence and presence of ACZ, respectively. (C) Effects of luminal 10^–4 M ACZ on Na⁺ transepithelial transport in CCDs isolated from Ncc^–/– mice. Statistical significance was assessed by 2-tailed Student’s unpaired t test. n = 5 in each group. (D) Effects of ACZ 10^–4 M on NDCBE activity in isolated CCDs. Tubules were isolated from wild-type mice. NDCBE activity was assessed by measuring changes in pH_i of intercalated cells when Na⁺ was removed and then readded from the perfusate. Both bath and perfusate solutions contained 25 mM HCO₃^– and 122 mM Cl^–. The bath solution was sodium-free to silence basolateral Na⁺/H⁺ exchanger activity. Traces represent the average of recordings from independent tubules. n = 4–5 independent tubules by group. Mean starting pH_i values were 7.03 ± 0.04 and 6.99 ± 0.05, in the absence and presence of ACZ, respectively.