Cellular coupling in the heart

Abstract

Traditionally, has muscle tentials Nonmyocytes oftenfocusedconsidered cells andcardiacareon that within electricallymyocytes—the generate barrierselectrophysiologthe action heart to excitable actionhear po ar potential propagation. Typically defined a extracellular matrix–producing cells, car diac fibroblasts are one of the largest non myocyte cardiac populations. However, the have been recognized to be important fo maintaining normal cardiac function and for mediating cardiac remodeling durin pathology, when their number substantiall increases (1). The presence of electrical coupling between fibroblasts and myocytes has been established in vitro and more recently demonstrated in situ (2–4). But definitive in vivo evidence has been lacking. On page 1480 of this issue, Wang et al. (5) report that fibroblasts and myocytes are electrically coupled in living mice. This finding could transform the understanding of cardiac connectivity and arrhythmogenesis, with profound implications for the management of heart disease patients. Wang et al. engineered an optogenetic transgenic mouse that expressed the light-sensitive channelrhodopsin 2 (CHR2) in fi-