Figure 5. Effects of apical and basal substitution of Cl⁻ on the I_sc elicited by dDAVP in wild-type and Scnn1b mutant L/L CCD cells.

Sets of confluent +/+^(L) (upper graphs) and L/L (lower graphs) CCD cells were incubated with apically and basally Cl⁻ substituted (Cl⁻, 0 mm) solutions (^) or with apical Cl⁻-substituted solution and basal HFM (Cl⁻, 126 mm) (•) as described in Methods. After equilibrating the traces, I_sc was measured before and after sequential additions of basal dDAVP (10⁻⁸m) and apical amiloride (10⁻⁵m). δI_sc represents the relative increase in I_sc induced by dDAVP. Amr I_sc and Ams I_sc represent the amiloride-resistant and -sensitive components, respectively, of I_sc measured in cells incubated with apical and basal Cl⁻-substituted solutions (open bars) or apical Cl⁻-substituted solution and basal HFM (filled bars). Values are means ± s.e.m. from five separate experiments for each condition tested. *P < 0.05, **P < 0.01, ***P < 0.001 between groups.