Effects of CBD (1 µM) on gating of a myotonia/hypoPP variant, P1158S. (a and b) Voltage dependence of activation as normalized conductance plotted against membrane potential at pH 7.4 (control: V_1/2 = −30.0 ± 3.3 mV, z = 3.1 ± 0.2, n = 8; CBD: V_1/2 = −32.7 ± 3.6 mV, z = 2.9 ± 0.2, n = 7; P > 0.05 for both V_1/2 and z) and pH 6.4 (control: V_1/2 = −23.0 ± 3.3 mV, z = 2.9 ± 0.2, n = 8; CBD: V_1/2 = −21.1 ± 3.3 mV, z = 2.5 ± 0.2, n = 8; P > 0.05 for both V_1/2 and z). (c and d) Voltage dependence of 200-ms F-I curve plotted against membrane potential (channels were held at −130 mV for 200 ms) at pH 7.4 (control: V_1/2 = −73.2 ± 2.6 mV, z = 2.9 ± 0.2, n = 7; CBD: V_1/2 = −83.0 ± 2.6 mV, z = 3.0 ± 0.3; P = 0.0260 for V_1/2 and P > 0.05 for z) and pH 6.4 (control: V_1/2 = −68.4 ± 3.0 mV, z = 2.7 ± 0.4, n = 5; CBD: V_1/2 = −81.7 ± 2.3 mV, z = 2.7 ± 0.3, n = 9; P = 0.0010 for V_1/2 and P > 0.05 for z). (e and f) Recovery from fast inactivation at 500 ms at pH 7.4 (control: τ_Fast = 0.0018 ± 0.006 s, τ_Slow = 0.15 ± 0.6 s, n = 7; CBD: τ_Fast = 0.24 ± 0.07s; τ_Slow = 2.5 ± 0.6 s, n = 6; P = 0.0347 for τ_Fast and P = 0.0245 for τ_Slow) and pH 6.4 (control: τ_Fast = 0.065 ± 0.04 s, τ_Slow = 0.75 ± 0.4 s, n = 7; CBD: τ_Fast = 0.13 ± 0.07 s; τ_Slow = 0.62 ± 0.1 s, n = 4; P < 0.05 for τ_Fast and P > 0.05 for τ_Slow). (g and h) Persistent currents measured from a 200-ms depolarizing pulse to 0 mV from a holding potential of −130 mV at pH 7.4 (control: percentage = 4.4 ± 1.2%, n = 4; CBD: percentage = 1.0 ± 0.2%, n = 4; *, P = 0.0339; n = 4) and pH 6.4 (control: percentage = 4.4 ± 2.1%, n = 6; CBD: percentage = 5.4 ± 1.2%, n = 5; P > 0.05). Error bars are SE in mean.