Isolation and amplification of cardiac pacemaking/conduction system cells and development of a pacemaking/conduction system in vitro using the expression of surrogate expression markers. Use of markers to identify and select for clusters of pacemaking “nodes” that are functionally coupled with adjacent contracting regions and generation of cell populations displaying electrical properties characteristic of specialized pacemaking/conducting cardiac myocytes for modeling the cardiac conduction system, testing of pharmaceuticals and for transplantation.