The two ions that are responsible for the initial depolarization of cardiac muscle as they travel from the outside of a muscle cell to the inside of the cell are ions.

The two ions are SODIUM AND CALCIUM IONS. Polarization refers to loss of polarization, that is, loss of the difference in charge between the inside and the outside of the plasma membrane of a muscle due to a change in permeability and migration of ion. When a heart muscle is depolarize, sodium ion and calcium ion channels open and they migrate into the cell from the outside.