Electrophysiology properties of neonatal cardiomyocytes (N-CMs) and induced pluripotent stem cell-derived cardiomyocytes (iPS-CMs). (A) Current clamp recordings revealed differentiation of neonatal cells into atrial and ventricle-like action potentials from cardiomyocytes. (B) Comparison of action potential parameters measured from N-CMs and iPS-CMs. Solid lines through distributions indicate population means. Dotted lines indicate 0 mV membrane potential (A) or population means (B), respectively. Data were compared using t-test. *P < 0.05 between both cell types. MDP, maximum diastolic potential; APD90, action potential duration at 90% of repolarization.