DIV-CN eliminates most of the gating charge movement associated with DIV. (A) Comparison of normalized ON gating currents for wild-type (black) and DIV-CN (red) channels in response to depolarizing voltage steps to −30, −10, and 0 mV after a 50-ms prepulse to −130 mV. Pore currents were blocked with CTX, which we have recently shown does not affect DIV gating charge movement, unlike tetrodotoxin (Capes et al., 2012). (B and C) ON gating currents were fit with a bi-exponential decay. The voltage dependence of the fast and slow time constants and their relative amplitudes for wild-type and DIV-CN channels is summarized in B and C, respectively (mean ± SEM; n ≥ 4).