Fig. 5.
Effects of allopregnanolone sulfate (APAS) on I–V curves of sodium currents in oocytes expressing Nav1.2 (a) (n = 5), Nav1.6 (b) (n = 7), Nav1.7 (c) (n = 5), or Nav1.8 (d) (n = 6) α subunits with β1 subunits. Currents were elicited using 50-ms depolarizing steps between −80 and 60 mV in 10-mV increments from a Vmax holding potential and elicited using 50-ms depolarizing steps between −60 and 60 mV in 10-mV increments from a V1/2 holding potential. (A) Representative INa traces from oocytes expressing Nav1.2 (left) and Nav1.8 (right) with the β1 subunit in both the absence and presence of 100 μmol/l of APAS at Vmax holding potential are shown. The effects of APAS on normalized I–V curves elicited from Vmax (B) and V1/2 holding potentials (C) are shown (closed circles, control; open circles, neurosteroids; cross, washout). Peak currents were normalized to the maximal currents observed from −20 to +10 mV. Data are presented as means ± SEM. Nav = voltage-gated sodium channel; Vmax holding potential = holding potential causing maximal current; V1/2 holding potential = holding potential causing half-maximal current; Wash = washout.