Fig. 2: Confocal microscopy of left ventricular myocardium from 21-year-old donor.

Image stacks were deconvolved to account for anisotropic blurring and corrected for depth-dependent signal attenuation. Example cross-sectional images from 3D stack for a WGA, b anti-RyR, and c anti-JPH2 antibody labeling. WGA served as a marker of the extracellular spaces and sarcolemma including t-system. d Overlay of a–c. e–h Zoom-ins of region in a–d marked with box in d. WGA-associated signals describe cross-sections of t-tubules. RyR- and JPH2-associated signals were apparent in small regions reflecting the clustering of these proteins. Histograms of sarcolemmal distances to i intracellular sites, j RyR clusters, and k JPH2 clusters. l Bar graph of sarcolemmal distances with error bars identifying their standard deviation. Scale bar in a marks 20 µm and applies to b–d. Scale bar in e marks 2 µm and applies to f–h.