Plateau phase of cardiac muscle is due to: (A) East Na + channel opening, (B) Opeaning of Ca++Na+ channels, (C) Opeaning of Slow Ca++ channels, (D) Opeaning of K + channels
Answer is C. Ca2+ influx through more slowly opening Ca2+ channels produces the plateau phase The initial depolarization is due to Na+ influx through rapidly opening Na+ channels Repolarization is due to net K+ efflux through multiple types of K+ channels Ref: Ganong's Review of Medical Physiology Twenty-Third Edition Page No:491