Effect of filamin on whole-cell transport mediated by αβγ-ENaC or α-ENaC overexpressed in Xenopus oocytes.
A, representative ENaC-mediated whole-cell currents recorded at −50 mV with the two-microelectrode voltage clamp in the presence of the standard Na+- or NMDG-containing solution, ± amiloride (10 μm), as indicated in an oocyte injected with αβγ-ENaC mRNA together with (lower panel) or without (upper panel) FLNAC mRNA. B, averaged amiloride-sensitive Na+ currents measured at −50 mV, from oocytes expressing αβγ-ENaC, αβγ-ENaC + FLNAC, or αβγ-ENaC + FLNBC. C, representative current-voltage (I-V) relationships obtained using a voltage ramp protocol with other conditions similar to A and B. D, effect of FLNAC on α-ENaC function, assessed by amiloride-sensitive Na+ currents. Shown are averages obtained from using oocytes expressing α-ENaC or α-ENaC + FLNAC (p < 0.001, between ± FLNAC, by unpaired t test), or water-injected oocytes. E, representative I-V curves obtained using a voltage ramp protocol with other conditions similar to C.