Fibroblast-myocyte connections in the heart

摘要

Five years ago, a viewpoint paper in this journal discussed the potential relevance of myocyte-nonmyocyte interaction for heart rhythm. At the time, the expression "cardiac nonmyocyte" was largely seen to be equivalent to fibroblast, and heart-rhythm relevant interaction was considered mainly in terms of electrotonic coupling between heterotypic cells, which-if present in vivo-was thought to form 3 principal configurations worthy of consideration: 1. Zero-sided connection: Nonmyocytes that are not elec-trotonically coupled to cardiac muscle cells (the "classic" case), where both cellular and acellular connective tissues act as potentially arrhythmogenic obstacles to electrical impulse propagation in the heart, possibly also forming polarization foci during electrical defibrillation. 2. Single-sided connection: Nonmyocytes that interact electrically with a single, functionally homogeneous group of cardiac muscle cells may affect local myocardial elec-trophysiology by forming current sinks that locally affect cardiomyocyte excitability, repolarization, and conduction. 3. Double-sided connection: Nonmyocytes that electrically interconnect structurally separate cardiomyocyte groups may serve as short- and long-range conductors, with consequences for activation pathways in health and disease.