Rhythmic beating of stem cell-derived cardiac cells requires dynamic coupling of electrophysiology and Ca cycling

►Inherent PKA activity drives basal Ca2+ cycling in EC cell-derived cardiac cells. ►L-type Ca2+ current synchronizes phases of local Ca2+ oscillators. ►Synchronized diastolic Ca2+ release activates Na+/Ca2+ exchanger current. ►Diastolic Na+/Ca2+ exchanger current strongly contributes cell automaticity. ►Rhythmic cell automaticity requires coupling of electrophysiology and Ca2+ cycling.