Fig. 8: INa alterations in TS1: regulation by Ca2+ and CaMKII.
a–d, Peak INa in the absence of intracellular Ca2+. a, Traces of INa in WT (top, in blue) and TS1 (bottom, in red) cardiomyocytes. Graph shows peak INa I-V relationships for WT (blue, n = 17 cells and N = 4 animals) and TS1 (red, n = 23 cells and N = 4 animals) (P = 0.025 at −40 mV, P = 0.006 at −35 mV and P = 0.025 at −30 mV; two-way ANOVA with Šidák post test). b, INa activation and availability curves for WT (blue, n = 14 cells and N = 4 animals) and TS1 (red, n = 13 cells and N = 5 animals) (P = 0.025 for availability and P = 0.091 for activation; two-tailed nested t-test). c, INa inactivation rates WT (blue, n = 17 cells and N = 4 animals) and TS1 (red, n = 23 cells and N = 4 animals) (two-way ANOVA P = 0.005; P = 0.009 at −35 mV, P = 0.003 at −25 mV and P = 0.003 at −15 mV; two-way ANOVA with Šidák post test). d, Recovery from inactivation of INa for WT (blue, n = 12 cells and N = 5 animals) and TS1 (red, n = 20 cells and N = 6 animals) (P < 0.0001; two-tailed F-test). e, Late INa in the absence of intracellular Ca2+. Left, representative recordings of WT (blue) and TS1 (red) cardiomyocytes. Late INa current was calculated by subtracting traces without and with TTX (10 µM). Right, graph shows the quantification of late INa for WT (n = 8 cells and N = 3 animals) and TS1 (red, n = 10 cells and N = 3 animals) (P = 0.034; two-tailed nested t-test). f, Representative traces (left) and quantification (right) of peak INa in physiological Ca2+ for WT (n = 20 cells and N = 9 animals), TS1 (n = 27 cells and N = 7 animals), TS1 + AIP (100 nM) (n = 12 cells and N = 3 animals) and TS1 + KN93 (1 µM) (n = 24 cells and N = 7 animals). g, Representative traces (left) and quantification (right) of late INa in physiological Ca2+ for WT (n = 12 cells and N = 5 animals), TS1 (n = 30 cells and N = 5 animals), TS1 + AIP (100 nM) (n = 10 cells and N = 3 animals) and TS1 + KN93 (1 µM) (n = 26 cells and N = 5 animals). Nested one-way ANOVA with Šidák post test (f,g). Each value is represented as mean ± s.e.m. NS, not significant, *P < 0.05, **P < 0.01 and ***P < 0.001.
