Cardiac Ion Channels

The movement of ions across cardiac cell membranes generates the electrical potentials that activate the heart. Today's molecular biology is providing breathtaking new insights into the regulation of this electrical activity, which is the basis of electrocardiography. Whereas only a few years ago depolarization and repolarization of heart cells were attributed to changing membrane resistance, cardiac action potentials are now understood in terms of structural changes in the proteins that control ion fluxes across the plasma membrane.Ions cross hydrophobic lipid membranes by passing through regulated pores formed by members of an extended family of ion-channel proteins. The opening and . . .