Figure 4

Effects of A735V mutation are reproducible from clone-to-clone and for different approaches of hiPSC-CMs. (a) Mean values (±s.e.m.) of upstroke velocities of two WT and two A735V mutant clones. There are no differences among WT clones or A735V clones, but differences between WT and A735V clones are highly significant (one way ANOVA with Tukey’s post-hoc comparison test F(3,78) = 26.32, p < 0.001). (b) Inter-experimental variability between different approaches with WT and mutant A735V hiPSC-CMs showing no changes in upstroke velocities among themselves, while WT versus A735V differed considerably from each other (one way ANOVA with Tukey’s post-hoc test F(6,75) = 12.82, p < 0.001). (c) Inter-experimental variability of mean maximal sodium current densities for WT and A735V mutant hiPSC-CMs (one way ANOVA with Tukey’s post-hoc test F(6,70) = 7.467, p < 0.001). (d) An increase in sodium channel density directly correlates to upstroke velocity acceleration of the same cells throughout the different hiPSC-CM approaches corroborating the effect of A735V sodium channel mutation on upstroke velocity (d, linear regression with R² = 0.9937 and F(1,5) = 749.9; n = 7-19). Coloured symbols represent mean values of different approaches as depicted in (b,c). (e) Sodium channel activation (G/G_max) and inactivation (I/I_max) curves of Na_V1.5 channels from WT and two clones of A735V hiPSC-CMs. Solid lines represent fits with Boltzmann functions. (f) Mid-voltages V_0.5 of sodium channel activation for two independent A735V clones as compared to WT hiPSC-CMs (one way ANOVA with Tukey’s post-hoc test F(2,74) = 37.76, p < 0.001). (g) Mid-voltages V_0.5 of sodium channel inactivation for two independent A735V clones as compared to WT hiPSC-CMs (one way ANOVA with Tukey’s post-hoc test, F(2,70) = 4.261, p < 0.05). Data volume in panels (a–c) and (f–g) is as indicated by numbers. (e) comprises the same cell numbers as in (f) and (g).