Cardiac muscles action potential at plateau is due to: (A) Influx of Na, (B) Efflux of K, (C) Influx of ca, (D) Influx of cl
Answer is C. 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