Fig. 3: Effects Na_V1.8 inhibition on intracellular Ca²⁺ handling.

a Representative line scan images of CaMKIIδc^+/T ventricular cardiomyocytes. b CaSpF data shown as mean ± SEM for wildtype (WT) (untreated: n = 58 cells/4 mice; PF-01247324: n = 41 cells/4 mice; A-806467: n = 41 cells/4 mice) and CaMKIIδc^+/T (untreated: n = 122 cells/8 mice; PF-01247324: n = 105 cells/7 mice; A-806467: n = 101 cells/8 mice). Data were analyzed by one-way ANOVA with post hoc Bonferroni’s correction. c Representative line scan images of human failing ventricular cardiomyocytes. d Data shown as mean ± SEM (untreated: n = 123 cells/14 patients; Autocamtide-2-related inhibitory peptide (AIP): n = 105 cells/15 patients; PF-01247324: n = 59 cells/10 patients; AIP + PF-01247324 = 89 cells/13 patients). Data were analyzed by one-way ANOVA with post hoc Bonferroni’s correction, Probability vs. untreated. e Representative Ca²⁺ transients stimulated at 1 Hz and caffeine-induced Ca²⁺ transients in ventricular cardiomyocytes from CaMKIIδc^+/T under untreated conditions. f Mean data ± SEM show no effect of PF-01347324 treatment on Ca²⁺ transient amplitude at 1.0, 2.0, and 4.0 Hz stimulation (n = 13 cells/5 mice) compared to untreated (n = 10 cells/5 mice). g Ca²⁺-transient decay (90% of Ca²⁺-removal) RT90 was unchanged in PF-01347324-treated cells (n = 11 cells/5 mice) compared to untreated (n = 8 cells/5 mice). Data were presented as mean values ± SEM. h Representative Ca²⁺ transients stimulated at 1 Hz and caffeine-induced Ca²⁺ transients in ventricular cardiomyocytes from CaMKIIδc^+/T treated with PF-01247324. i Diastolic Ca²⁺ after addition of PF-01347324 (n = 13 cells/5 mice) compared to untreated cells (n = 10 cells/5 mice) at different stimulation frequencies was unchanged (one-way ANOVA with post hoc Bonferroni’s correction, Fig. 3f, g, i). Data were presented as mean values ± SEM. j Mean and individual values ± SEM of caffeine-induced Ca²⁺ transients (untreated: n = 7 cells/4 mice, PF-01247324: n = 11 cells/5 mice) did not differ between the groups (Student’s t-test). k Ca²⁺-reuptake into the SR was not affected by inhibition of Na_V1.8 (untreated: n = 7 cells/4 mice, PF-01247324: n = 11 cells/5 mice), analyzed by Student’s t-test. Data were presented as mean values ± SEM.