Fig. 3.

FGF14 knockdown leads to a decrease in XE-991–sensitive outward currents. (A) Currents from DIV10–11 neurons recorded in the presence of TTX, Cd²⁺, and 4-AP were elicited from a holding potential of −90 mV to steps from −100 mV to 40 mV (n, Scr = 16, 14KD = 21, 13KD = 16). KCNQ currents were defined as the noninactivating component of outward potassium current sensitive to 20 μm of XE-991. KCNQ currents from neurons transfected with FGF14-targeted shRNA (14KD) but not FGF13-targeted shRNA (13KD) neurons were smaller than currents from neurons transfected with a scrambled control shRNA (Scr). (Scale bar, 1 nA and 200 ms.) (B) Current–voltage relationships plotted for Scr, 13KD, and 14KD. Shown are basal current densities before application of XE-991 and current densities of the XE-991–sensitive component. (C) Maximum current amplitudes from the last 100 ms of the 20-mV voltage step were significantly lower for 14KD than for Scr or 13KD. A smaller component of this current was XE-991 sensitive in 14KD neurons, indicating a loss of KCNQ currents. XE-991–resistant currents were not significantly changed although a decremental trend was observed (normalized mean ± error propagated SEM, *P < 0.05, ANOVA followed by Fisher’s least significant difference (LSD).