Electrophysiology of ion channels of the heart

The contribution of Na+, Ca2+, and various K+ currents to the shape of the cardiac action potential is outlined based on the relation between electrophysiological properties and structure of channel molecules. These currents have also been found in human ventricular myocytes, where the most prominent K+ current is a transient outward current that is not influenced by methylsulfonanilide antiarrhythmic drugs. Combined knowledge of electrophysiological and molecular properties of ion channels is likely to form the basis for rational design of future drugs.