Cardiac muscles action potential at plateau is due to
Ca2+ influx through more slowly opening Ca2+ channels (the Ca2+ current, ICA) produces the plateau phaseRepolarization is due to net K+ efflux through multiple types of K+ channelsThe initial depolarization is due to Na+ influx through rapidly opening Na+ channels Ref: Ganong's Review of Medical Physiology Twenty-Third Edition pg:491
Influx of Na
Efflux of K
Influx of ca
Influx of cl
Cardiovascular system