As in all other cells, the resting potential of a pacemaker cell (-60mV to -70mV) is caused by a continuous outflow or leak of potassium ions through ion channel proteins in the membrane that surrounds the cells.hese cells form the atrioventricular node (or AV node), which is an area between the left atrium and the right ventricle within the atrial septum, will take over the pacemaker responsibility. The cells of the AV node normally discharge at about 40-60 beats per minute, and are called the secondary pacemaker.