<prompt> The physiological change occurs in a cardiac muscle cell when there is plateau phase of action potential is:Influx of NaInflux of Ca2Influx of KClosure of voltage gated K channels  <response>: The transmembrane action potential of single cardiac muscle cells is characterized by, Rapid depolarization phase 0 Initial rapid repolarization phase 1 Plateau phase 2 Slow repolarization process phase 3 that allows return to the resting membrane potential phase 4. The initial depolarization is due to Na influx through rapidly opening Na channels the Na current, INa. The inactivation of Na channels contributes to the rapid repolarization phase. Ca2 influx through more slowly opening Ca2 channels the Ca2 current, ICa produces the plateau phase, and repolarization is due to net K efflux through multiple types of K channels. Ref: 2012. Chapter 29. Origin of the Heabeat the Electrical Activity of the Hea.In Barrett K.E., Boitano S, Barman S.M., Brooks H.L. Eds, Ganongs Review of Medical Physiology, 24e. 