Fig. 4

A Typical action potentials (APs) of cardiomyocytes isolated from a 10-month-old wild type (WT) (top panel) and plna R14del mutant (bottom panel) zebrafish, paced at 1 Hz. B Average AP parameters at 1 Hz pacing (mean ± SEM, WT n = 12, plna R14del n = 13, unpaired Students t-test). C AP duration at 90% of repolarization (APD₉₀) at 0.2–4 Hz pacing (mean ± SEM, WT n = 10, plna R14del n = 13, unpaired Students t-test). D Two consecutive APs during 4 Hz pacing in a WT (top panel) and plna R14del (bottom panel) cardiomyocyte. The plna R14del cardiomyocyte showed an AP alternans where a long AP is followed by a short AP. E Average APD₉₀ difference between two consecutive APs (alternans) during 4 Hz pacing (mean ± SEM, *p = 0.044, WT n = 10, plna R14del n = 13, Mann–Whitney rank-sum test). Wild type are highlighted in black and plna R14del in red. WT wild type, Hz Hertz, mV millivolt, ms milliseconds, V/s Volts per second, RMP resting membrane potential, APA_max maximal action potential amplitude, APA_plat action potential amplitude at plateau phase, 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.