Representative micrographs of transverse sections of rat hearts sham and 6 weeks after pulmonary artery banding (PAB) procedures. A, Immunofluorescent detection of vimentin‐positive fibroblasts (green) and those displaying the presence of Ki‐67 proliferative antigen (red). Cell nuclei were stained blue, with 4′,6‐diamidino‐2‐phenylindole (DAPI). Bars=15 μm. B, Wheat germ agglutinin (WGA) interacting with cardiac myocyte cell membranes, detected with green fluorescein isothiocyanate (FITC; fluorescein) staining. Bar=20 μm. C, Hematoxylin and eosin staining for cardiomyocyte cross‐sectional area. Bar=20 μm. D, The bar graphs depict morphometric assessment of cardiac myocyte areas (n=5, with 200 cells per section). Values are expressed as medians and interquartile range. E, Immunohistochemical analysis of natriuretic peptide (NPPA) in cardiac muscle of sham and PAB rats. Bar=50 μm. HP indicates hinge point; LV, left ventricle; NPPA, Natural antisense transcript of natriuretic peptide precursor A; and RV, right ventricle. *P<0.05, **P<0.001 vs sham.