Cardiac Action Potentials, Ion Channels, and Gap Junctions

It is the interplay between various ion channels within the membranes of cardiomyocytes that is responsible for depolarization and repolarization of the heart cells. Cell-to-cell coupling between myocytes is mediated via gap junction proteins and is involved in overall propagation of action potentials throughout the heart. In this chapter, different phases of the action potential of heart cells are discussed, and the role and characteristics of the most important ion channels that are active during these phases are conferred. Differences in the expressions of the various ion and gap junction channels under normal and certain pathological conditions are described.