WWWW characterization; CBD stabilizes inactivation in the fenestration-altered construct. (a and b) Conductance voltage (GV) of the construct compared with WT-Nav1.4 (Nav1.4: V_1/2 = −19.9 ± 2.7 mV, z = 2.8 ± 0.3, n = 5; WWWW: V_1/2 = −11.4 ± 0.4 mV, z = 2.0 ± 0.1; P = 0.0113 for V_1/2 and P > 0.05 for z, n = 7) and 200-ms F-I curve (Nav1.4: V_1/2 = −64.1 ± 2.4 mV, z = −2.7 ± 0.3, n = 8; WWWW: V_1/2 = −47.6 ± 0.5 mV, z = 1.7 ± 0.04, n = 5; P < 0.05 for both V_1/2 and z). Both channels are full availability at −110 mV. (c and d) Voltage dependence of 200-ms F-I curve before and after control (c; extracellular solution [ECS]) and CBD (d; 10 µM) in WWWW construct (before control: V_1/2 = −54.7 ± 5.1 mV, n = 6; after control: V_1/2 = −54.2 ± 5.4 mV, n = 6; before CBD: V_1/2 = −48.8 ± 8.8 mV, n = 3; after CBD: V_1/2 = −72.7 ± 5.7 mV, n = 3, P = 0.0068 for CBD in matched-pair analysis). The ECS experiment was performed to ensure that hyperpolarization shifts in the CBD condition are not due to possible confounding effects associated with fluoride in the internal (CsF) solutions. (e and f) Representative families of inactivating currents before and after perfusion. CBD does not block peak currents but shifts the F-I curve to the left. (g) Averaged shift in the midpoint of F-I curve before and after perfusion. *, P < 0.05. Error bars are SE in mean.