Figure 6

Representative images of SHG showing the arrangement of myosin fibers in sham and TAC-operated hearts with overview images (top) and magnified images at the ROI (bottom). (A) The myosin fibers show a linear and symmetric arrangement in the sham heart. The intercalated disks between myosin fibers do not emit SHG and appear dark which is pointed by a blue arrowhead. (B) In the TAC heart, undulated myosin fibers are located within the muscle mass as shown by a green arrowhead. (C) The cross-linked collagen fibers can be seen in the myocardium causing disruption and rupture of myosin fibers indicated by red arrowheads. Scale bars: 50 µm in overview images (top panel) and 20 µm in magnified ROI images (bottom panel). (D) Image analysis of myosin morphology in SHG micrographs of TAC and sham hearts. The power spectral density (PSD) was computed for each image, see the example of a TAC (bottom) and sham micrograph (top) by 2D fast Fourier transformation (FFT). The 2D PSD shows a pattern reflecting the orientation of myosin strands, the periodicity of the striation as well as the degree of undulation. (E) After azimuthal average, a single scalar indicator value can be computed from the 1D PSD, which differs between TAC and sham morphology with high statistical significance (see main text).