Emerging Function of Cardiac Macrophages Ushers in a New Era for the Electrophysiology of the Heart

Maintaining a coordinated heart rhythm is essential for maintaining the heart's pumping function and blood circulation. Every heartbeat is generated by electrical impulse propagation that is passing through gap junctions, which are composed of connexin proteins. In mammalian hearts, Cx43, Cx40, Cx45, and Cx30.2 are expressed and regulated by post-translational modification. Cardiac macrophages account for only a small number of total heart cells, but they reside all around the heart. They are primarily established prenatally, and they arise from embryonic yolk sac progenitors. Recently, increasing attention has been directed toward novel roles for cardiac resident macrophages, especially in the heart's electrical impulse conduction. Here, we provide an overview of the recent findings on connexins, with a focus on the emerging function of cardiac macrophages, and we discuss the future directions of treatment for heart disease.