E143K mutation leads to time-dependent morphological changes in mice. (A) Histology and structure in representative E143K and WT hearts. H&E and Masson’s trichrome stained LV sections from 5 to 6 (left) and 11 to 12 (right) mo-old female and male E143K mice compared with WT mice. Scale bar, 50 µm. (B) Electron microscopy images of 11 mo-old E143K vs. WT-hearts. Note Z-line streaming (arrowhead) and the areas with disorganized sarcomeric structures (asterisk) in E143K-hearts. Scale bars: 2 µm (upper panel), 1 µm (middle panel) and 0.2 µm (lower panel). (C) Hydroxyproline (HOP) content, and stress-related gene expression in E143K vs. WT hearts. HOP was measured in LV tissue from ∼11 mo-old E143K (2M, 3F) compared with WT (2M, 3F) mice. Expression of stress-related genes was assessed in ∼6 mo-old E143K (2M, 3F) compared with WT (2M, 3F) mice. M, blue symbols; F, red symbols. Data are presented as mean ±SEM, t-test, *P < 0.05 vs. WT.