Functional gap junctions in cardiac clusters.

<p><b>A:</b> Original recording of a iPS cell-derived cardiomyocyte cluster loaded with the gap junction permeable dye fluo-4 at baseline (left panel, scale bar 10 μm), immediate after photobleaching of a single cell (mid panel, arrow) and 10 minutes later (right panel). <b>B:</b> Analysis of fluorescence intensity as a function of time at two regions of interest: the bleached cell and an adjacent donor cell. The fluorescence recovery after photobleaching (FRAP) could be fit with a single exponential with a recovery rate constant k of 2.94 ms. The simultaneous drop in fluorescence in the adjacent donor cell that could also be fit with a single exponential (k = 0.51 ms).