Injection of hyperpolarizing current is sufficient to regulate DAD and TA in isolated S3A cardiomyocytes. (A) Representative APs traces of S3A isolated cardiomyocytes in the absence or presence of 1 μM Iso. Hyperpolarizing currents (20–12 pA) were injected to maintain the resting membrane potential close to −68 mV (value observed in WT cardiomyocytes). Black arrows indicate electrical stimulation pulse. Red arrows indicate TAs. Red asterisks display DADs. (B) Quantification of DADs observed in 1 min. (C) Quantification of DADs amplitude. (D) Quantification of TAs detected in 1 min. The number in parentheses indicates biological replicates. Comparisons between groups were made using nested-ANOVA plus Tukey’s post-hoc test.