Fig. 7

A Typical action potentials (APs) of plna R14del isolated adult cardiomyocytes at baseline (black line) and after incubation with 5 µM istaroxime (orange line), paced at 1 Hertz (Hz). B Average AP parameters of plna R14del isolated adult cardiomyocytes at baseline (black bars) and after incubation with 5 µM istaroxime (orange bars), at 1 Hz pacing (mean ± SEM, APD₂₀: *p = 0.030, APD₅₀: *p = 0.022, APD₉₀: *p = 0.020, baseline n = 6, istaroxime n = 6, paired Student’s t-test). C Typical action potentials (APs) of plna R14del isolated adult cardiomyocytes at baseline (black line) and after incubation with 5 µM istaroxime (orange line), paced at 4 Hz. The plna R14del cardiomyocyte showed an AP alternans at baseline, where a long AP is followed by a short AP. D Average APD₉₀ difference between two consecutive APs (alternans) at baseline and after incubation with 5 µM istaroxime, during 4 Hz pacing (mean ± SEM, *p = 0.039, baseline n = 6, istaroxime n = 6, paired Student’s t-test). All measurements were performed in three experimental replicates. Baseline condition is highlighted in black and treated in orange. Hz Hertz, mV millivolt, APD₂₀ AP duration at 20% of repolarization, APD₅₀ AP duration at 50% of repolarization, APD₉₀ AP duration at 90% of repolarization. Source data are provided as a Source Data file.