High Quality Content by WIKIPEDIA articles! A pacemaker action potential is the kind of action potential that provides a reference rhythm for the network. This contrasts with pacemaker potential or current which drives rhythmic modulation of firing rate. Some pacemaker action potentials generate rhythms for the heart beat (sino-atrial node) or the circadian rhythm in the suprachiasmatic nucleus.In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a stereotyped trajectory.