Fig. 4. Effects of symmetric anion substitution and apical addition of DPC on basal I_sc. (A) I_sc trace showing the inhibitory effects of 10 µmol l^-1 and 100 µmol l^-1 DPC on basal anion current in a tissue pretreated with 100 µmol l^-1 amiloride. (B) Magnitude of basal I_sc inhibition produced by apical DPC, 100 µmol l^-1 (N=5), Cl^- replacement with methane sulfonate (N=7), HCO₃^- replacement with Hepes (N=6) and 0.5 mmol l^-1 DIDS added to the apical solution (N=5).