Panel A shows a schematic of the N terminal region of FGF14A with labeled mutation sites and sequence variations across different constructs. Panel B shows a stimulation protocol diagram and corresponding current traces illustrating responses during repetitive pulse trains for WT and mutated FGF14A constructs with scale bars for current and time. Panel C shows representative paired pulse current traces for recovery from inactivation across constructs with different recovery intervals indicated. Panel D shows a plot of normalized current versus pulse number in train with pulse number on the horizontal axis and normalized current on the vertical axis. Panel E shows a plot of fractional current versus train frequency with train frequency in hertz on the horizontal axis and fractional current on the vertical axis. Panel F shows plots of recovery curves with recovery time in milliseconds on the horizontal axis and ratio of peak currents P2 divided by P1 on the vertical axis, including fitted curves. Panel G shows scatter plots comparing fractional amplitudes of fast and slow components across constructs. Panel H shows scatter plot of fast recovery time constants with time constant in milliseconds on the vertical axis and conditions on the horizontal axis. Panel I shows scatter plot of slow recovery time constants with time constant in milliseconds on the vertical axis and conditions on the horizontal axis.
Evaluation of LTI mediated by FGF14A N-terminal mutations. (A) Schematic of FGF14A mutation sequences. (B) 10 pulse 5 Hz train-mediated inhibition for various FGF14A-mutated constructs. (C) Example currents from paired-pulse protocol for recovery from inactivation for various constructs. (D) NaV attenuation during 5 Hz 10P trains. (E) Fractional attenuation of INa for 10th pulse in trains of different frequencies. (F) Time course of recovery from inactivation for the indicated constructs, along with best fits of single or double exponential functions. (G) Comparison of fraction of fast and slow amplitude components for FGF14A and FGF14A_2Q. (H) Comparison of fast recovery from inactivation for different constructs. (I) Comparison of slow recovery from inactivation for FGF14A and FGF14A_2Q. Statistical comparisons are given in Table 4. *P < 0.05 and ****P < 0.0001