Toward a molecular view of cardiac arrhythmogenesis

Clinical evidence strongly suggests that the electrophysiologic behavior of the heart, and its response to drugs, is a highly dynamic process. Ion channels are the fundamental molecular units determining cardiac excitability. The cloning of ion channels that are responsible for the generation and maintenance of the cardiac action potential will enable studies of the molecular mechanisms underlying the highly heterogeneous nature of cardiac electrophysiology. The molecular bases of important pathophysiologic events, such as acute regulation of channel function by phosphorylation or drug block, or the long-term electrophysiologic changes accompanying diseases such as hypertension, are now being elucidated. Identification of these molecular mechanisms may point to novel approaches to the treatment of cardiac arrhythmias.