Cardiac cell-cell junctions in health and disease: Electrical versus mechanical coupling

Intercalated discs are the membrane sites where individual cardiomyocytes are connected to each other. Adherens-, desmosomal-, and gap junctions are situated in the intercalated disc and ensure mechanical coupling between cells and enable propagation of electrical impulses throughout the heart. A number of cardiac disorders, for example arrhythmogenic right ventricular dysplasia/cardiomyopathy, have been described in which an impaired mechanical coupling leads to electrical dysfunction, with occurrence of fatal arrhythmias. In this article the interaction between electrical and mechanical coupling is explored by reviewing studies performed in patients, animals, and in vitro. In these studies the effect of changes in protein composition of a mechanical junction on the electrical junction, and vice versa were investigated. It is shown that impaired electrical coupling does not change mechanical coupling. However, impaired mechanical coupling largely affects electrical coupling.