Figure 3. Panel A shows paired pulse... | Rockefeller University Press

Figure 3.

$Onset and recovery from LTI differs among FGF-A homologue. (A) The indicated paired pulse protocol (top) was used to assess the time course of recovery from inactivation. Cells were held at −80 mV. An initial 10 ms depolarization to 0 mV (pulse 1, P1) was followed after variable recovery times (0.1 ms to 15 s) by a 25 ms step to 0 mV (pulse 2, P2). A 1 s step to −120 mV separated each paired pulse pair to permit full recovery from inactivation. From top to bottom, superimposed P1- (left) and P2- (right) elicited currents for NaV1.2 alone (WT) or coexpressed with each FGF-A isoform (FGF14A, FGF13A, FGF12A, and FGF11A) are shown. Red traces show INa following recovery intervals of 1, 10, 100, 1,000 and 10,000 ms. (B) Averaged time course of fractional recovery following inactivation for WT (black), WT+FGF14A (red), WT+FGF13A (blue), WT+FGF12A (magenta), or WT+FGF11A (green). INa elicited by P2 was normalized to IPEAK measured in P1 (P2/P1) and plotted as a function of different recovery intervals. Solid lines show single (for WT) or double (for WT+FGF-A) exponential fits to data points (mean ± SD) (values in Table 4). (C) Scatter plots of fast (τf, top panel) and slow (τs, bottom panel) time constants of recovery for each construct with means ± SD along with values for individual cells. See Table 2 for statistical comparisons. (D) Scatter plots of fractional amplitudes of fast (Af: top panel) and slow (As: bottom panel) recovery components for each construct along with values for individual cells. Data are expressed as mean ± SD (Table 2). Although Af ∼ 1−As, each parameter is plotted separately here for illustrative purposes. Fit parameters, statistics, and N are provided in Table 2. **P < 0.01, ***P < 0.001, and ****P < 0.0001. Refer to the image caption for details.$ Panel A shows paired pulse protocol schematic on top with P1 and P2 steps and recovery intervals, along with representative current traces for P1 on the left and P2 on the right, comparing NaV1.2 alone and with FGF14A, FGF13A, FGF12A, and FGF11A, with colored traces indicating different recovery times and scale bars for current and time. Panel B shows recovery curves of fractional current (P2 divided by P1) versus recovery time on a logarithmic scale with data points, error bars, and fitted curves for wild type and each FGF-A isoform. Panel C shows scatter plots of fast and slow recovery time constants with individual data points, mean values, and error bars for each condition. Panel D shows scatter plots of fractional amplitudes of fast and slow recovery components with individual data points, mean values, and error bars across conditions.

Onset and recovery from LTI differs among FGF-A homologue . (A) The indicated paired pulse protocol (top) was used to assess the time course of recovery from inactivation. Cells were held at −80 mV. An initial 10 ms depolarization to 0 mV (pulse 1, P₁) was followed after variable recovery times (0.1 ms to 15 s) by a 25 ms step to 0 mV (pulse 2, P₂). A 1 s step to −120 mV separated each paired pulse pair to permit full recovery from inactivation. From top to bottom, superimposed P₁- (left) and P₂- (right) elicited currents for Na_V1.2 alone (WT) or coexpressed with each FGF-A isoform (FGF14A, FGF13A, FGF12A, and FGF11A) are shown. Red traces show I_Na following recovery intervals of 1, 10, 100, 1,000 and 10,000 ms. (B) Averaged time course of fractional recovery following inactivation for WT (black), WT+FGF14A (red), WT+FGF13A (blue), WT+FGF12A (magenta), or WT+FGF11A (green). I_Na elicited by P₂ was normalized to I_PEAK measured in P₁ (P₂/P₁) and plotted as a function of different recovery intervals. Solid lines show single (for WT) or double (for WT+FGF-A) exponential fits to data points (mean ± SD) (values in Table 4). (C) Scatter plots of fast (τ_f, top panel) and slow (τ_s, bottom panel) time constants of recovery for each construct with means ± SD along with values for individual cells. See Table 2 for statistical comparisons. (D) Scatter plots of fractional amplitudes of fast (A_f: top panel) and slow (A_s: bottom panel) recovery components for each construct along with values for individual cells. Data are expressed as mean ± SD (Table 2). Although A_f ∼ 1−A_s, each parameter is plotted separately here for illustrative purposes. Fit parameters, statistics, and N are provided in Table 2. **P < 0.01, ***P < 0.001, and ****P < 0.0001.