Fig. 4.

Newly grown LTTs in KO cardiomyocytes contain NCX apposing RyR in the SR. (A–C) Representative confocal images of cardiomyocytes stained for CaV1.2 (A), NCX (B), and RyR (C). (D) Images from B and C were thresholded using the Otsu method, and pixels above threshold in both images are shown in white pixels. Red arrows indicate longitudinal segments where NCX and RyR are proximal. Histograms: Relative abundance of LTTs in KO normalized to FF (n = 8–16). Mean FFTs of confocal images (Right, n = 11–17) show unaltered labeling of CaV1.2, NCX, and RyR in the transverse segments and increased labeling of NCX and RyR but not CaV1.2 in the LTTs. A.U., arbitrary units; *P < 0.05.