The article deals with the energy supply by mitochondria to the processes of formation of myocytes of conduction system and the contractile myocardium. The energy consumption for synthesis of channel-forming proteins, ion carrier proteins, and the operation of ion pumps, which play a key role in imparting a vital property to cardiomyocytes — the ability to generate and conduct bioelectric potentials required to initiate myocardium contraction are discussed. The structure, properties and role of various ion channels and ion currents in mechanisms of generation of bioelectric potentials by pacemaker cells are considered. Examples of the relationship between disorders in the functioning of ion channels and ion pumps with the progress of cardiac arrhythmias are given.