(A-B) Representative action potential (APs, 1.0 Hz pacing) and summary of APD at 50%, 75% and 95% repolarization for 0.5 and 1.0 Hz pacing in WT and B56α KO myocytes. (C-D) AP amplitudes (APA) and maximum upstroke velocity (dv/dtmax) in WT and B56α KO myocytes. Results are shown for 0.5 and 1.0 Hz pacing frequencies (for B-D, WT, N=3; n= 9 and B56α KO, N=3; n=8; *p<0.05).