obsolete P-type sodium:potassium-exchanging transporter activity involved in regulation of cardiac muscle cell membrane potential (obsolete GO:0086037)
OBSOLETE. Enables the transfer of a solute or solutes from one side of a membrane to the other according to the reaction: ATP + H2O + Na+(in) + K+(out) = ADP + phosphate + Na+(out) + K+(in), that contributes to regulating the membrane potential of a cardiac muscle cell.