Effects of allopregnanolone sulfate (APAS) on channel activation in oocytes expressing Na_v1.2 (a) (n = 5), Na_v1.6 (b) (n = 7), Na_v1.7 (c) (n = 5), or Na_v1.8 (d) (n = 6) α subunits with β₁ subunits from V_max (A) or V_1/2 holding potentials (B). Closed circles, open circles, and cross represent control, the effect of neurosteroids, and washout, respectively. Data are expressed as means ± SEM. Activation curves were fitted to the Boltzmann equation; V_1/2 is shown in table 2. Na_v = voltage-gated sodium channel; V_max holding potential = holding potential causing maximal current; V_1/2 holding potential = holding potential causing half-maximal current; Wash = washout.