[Molecular structure and expression of ion channels in the heart]

Ion channels are essential for the generation and maintenance of the cardiac action potential. The successful cloning of ion channels has shed considerable light into their structure and function. The combination of molecular biological and electrophysiological studies has paved the ground to develop general concepts for understanding properties of these channels, such as gating mechanism, kinetics of activation and inactivation, ion selectivity and pharmacological properties. Recently, several cDNAs encoding cardiac inwardly rectifying K+ channels, including classical inwardly rectifying, G-protein-gated, and ATP-sensitive K+ channels, have been isolated. Identification of these molecular mechanisms may point to novel approaches to the treatment of cardiac arrhythmias. This review focuses on the molecular properties and functional roles of cardiac ion channels.