Comparison of electrophysiological properties of embryonic and adult heart cells.

Almost any membrane or structural property of cultured embryonic heart cells is identical to that of nodal pacemaker cells in the adult myocardium. The present electrophysiological data show that single cultured cells are advantageous to the study of cardiac impulse generation. Evidence is presented for the presence of a Na/K pump system, the dominant role of the slow Ca-inward current in excitation but not in automaticity and the susceptibility of automaticity to changes in membrane potential induced by current injection.