<prompt> Plateau phase of cardiac muscle is due toEast Na channel openingOpeaning of CaNa channelsOpeaning of Slow Ca channelsOpeaning of K channels  <response>: 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: Ganongs Review of Medical Physiology Twenty-Third Edition Page No:491 