Evolving form to fit function: cardiomyocyte intercalated disc and transverse-tubule membranes

The vertebrate cardiac myocyte has evolved a highly organized cellular membrane architecture and cell-cell contacts in order to effectively transmit precisely timed and homogeneous depolarizing waves without failure (>2 billion times/human life span). Two unique specialized membrane domains, the intercalated disc and the transverse tubule (T-tubule), function to ensure the rapid and coordinated propagation of the action potential throughout the heart. Based on their critical roles in structure, signaling, and electric inter- and intracellular communication, it is not surprising that dysfunction in these membrane structures is associated with aberrant vertebrate physiology, resulting in potentially fatal congenital and acquired disease. This chapter will review the fundamental components of cardiomyocyte intercalated disc and transverse-tubule membranes with a focus on linking dysfunction in these membranes with human cardiovascular disease.