Figure 1.
Properties of NaV1.2 currents coexpressed with different FGF-A homologues. (A) Example NaV1.2 currents recorded from HEK293T cells following transient expression of NaV1.2 cDNA alone (WT) or together with cDNA for the indicated A-type FGF proteins (FGF14A, FGF13A, FGF12A, and FGF11A). Currents were evoked by 25-ms depolarizing pulses from −80 to +60 mV in 5 mV increments (protocol on top). (B) Effect of FGF-A-homologues on voltage-dependent activation of NaV1.2 channels. Averages of individual GV relationships were generated as described in Materials and methods. Solid lines represent Boltzmann fits to the data. Values in Table S1. (C and D) Plots of mean Vh (C) and z (D) parameters from averaged GV curves with points plotting values from individual cells. (E) Voltage dependence of fast inactivation time constants (τi) for WT NaV1.2 is compared with those resulting from coexpression with each of the FGF-A isoforms. τi was obtained by fitting the decay phase of each current trace in panel A with a single exponential function (see Materials and methods). (Table S1 for statistical comparisons). (F) Comparison of τi at 0 mV for each condition (mean ± SD) with statistics given in Table S1. Statistical comparisons in C and D were performed using an ANOVA test with Tukey correction for multiple comparisons. In F, comparison was made with Welch ANOVA with Dunnett’s correction for multiple comparisons. ****P < 0.0001. Refer to the image caption for details. Panel A shows representative sodium current traces with an inset voltage protocol on top, comparing NaV1.2 alone and with FGF14A, FGF13A, FGF12A, and FGF11A, with scale bars for current and time. Panel B shows conductance–voltage curves of normalized conductance versus command potential with individual data points and fitted curves, separated for FGF14A, FGF13A, FGF12A, and FGF11A comparisons with wild type. Panel C shows scatter plots of half activation voltage values with individual data points, mean markers, and error bars for each condition. Panel D shows scatter plots of slope factor values with individual data points, mean markers, and error bars across conditions. Panel E shows plots of fast inactivation time constants versus command potential with data points, error bars, and fitted curves for wild type and each FGF-A isoform. Panel F shows scatter plot of inactivation time constants at zero millivolts with individual data points, mean with error bars, and statistical significance indicators.

Properties of Na V 1.2 currents coexpressed with different FGF-A homologues. (A) Example NaV1.2 currents recorded from HEK293T cells following transient expression of NaV1.2 cDNA alone (WT) or together with cDNA for the indicated A-type FGF proteins (FGF14A, FGF13A, FGF12A, and FGF11A). Currents were evoked by 25-ms depolarizing pulses from −80 to +60 mV in 5 mV increments (protocol on top). (B) Effect of FGF-A-homologues on voltage-dependent activation of NaV1.2 channels. Averages of individual GV relationships were generated as described in Materials and methods. Solid lines represent Boltzmann fits to the data. Values in Table S1. (C and D) Plots of mean Vh (C) and z (D) parameters from averaged GV curves with points plotting values from individual cells. (E) Voltage dependence of fast inactivation time constants (τi) for WT NaV1.2 is compared with those resulting from coexpression with each of the FGF-A isoforms. τi was obtained by fitting the decay phase of each current trace in panel A with a single exponential function (see Materials and methods). (Table S1 for statistical comparisons). (F) Comparison of τi at 0 mV for each condition (mean ± SD) with statistics given in Table S1. Statistical comparisons in C and D were performed using an ANOVA test with Tukey correction for multiple comparisons. In F, comparison was made with Welch ANOVA with Dunnett’s correction for multiple comparisons. ****P < 0.0001.

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