Some CCs from FGF14 KO mice exhibit slow recovery from inactivation. (A) A standard paired-pulse protocol was applied to a CC from a WT mouse. Left (P1): Overlays of currents elicited by first pulse to 0 mV are shown. Right: Currents evoked by a second test pulse (P2) after recovery intervals at −80 mV are shown. (B) For the same cell as in A, recovery was examined after a 10-Hz train of 10 pulses, with P1 and P2 currents as indicated. The variable duration recovery interval was applied at the end of the 10-Hz train. (C and D) Identical protocols were applied to CC from a FGF14 KO mouse. Note marked fast recovery (C) and the absence of diminution of peak Nav current during train. (E and F) Another CC from an FGF14^−/− mouse that exhibited a slow component of recovery from inactivation. Cell was from same tissue slice as that in C and D. (G) Fractional recovery for the WT CC following a single step to 0 mV (1P) and following 10 steps to 0 mV (10P). Two exponential fit values were, for 1P, A_f = 0.52 ± 0.01, τ_f = 8.9 ± 0.7 ms, A_s = 0.48 ± 0.02, and τ_s = 572.6 ± 74.9 ms; while, after 10P, A_f = 0.35 ± 0.01, τ_f = 9.9 ± 0.8 ms, A_s = 0.63 ± 0.01, and τ_s = 604.3 ± 41.9 ms. (H) Fractional recovery following both 1P and 10P were fit with single exponentials. Following 1P, τ_f = 6.8 ± 0.3 ms, while following 10P τ_f = 7.1 ± 0.5 ms. (I) 1P recovery was fit with A_f = 0.65 ± 0.01, τ_f = 10.1 ± 0.6 ms, A_s = 0.41 ± 0.12, and τ_s = 2,252.5 ± 1,209.7 ms. After 10P, A_f = 0.28 ± 0.01, τ_f = 7.5 ± 0.5 ms, A_s = 0.88 ± 0.06, and τ_s = 2,379.6 ± 2,252.5 ms. (J) Diminution in peak Nav current amplitude during the 10P protocol shown in B, D, and F for the three cells.