Histology change of the heart. A) Total myocardial fibrosis. Transverse section of left ventricle stained with Sirius Red and observed under light and polarized microscope. Whole collagen is red stained and indicated by arrows. Type I collagen is green-yellow, while Type III collagen is orange-red. Bar. 50 um. *p < 0.01 vs. control, p < 0.05 vs. HF, † p < 0.05 vs HF+ CoPP B) Perivascular fibrosis. Transverse sections of intramuscular arteries with perivascular fibrosis stained with Sirius Red and observed under light and polarized microscope. Bar. 100 μm. *p < 0.01 vs. control, #p < 0.05 vs.HF. C) Myocyte cross-sectional area. Left ventricular myocyte cross-sectional areas stained with hematoxylin. The myocyte cross-sectional area and myocardial fibrosis were quantitatively analyzed with Image Pro-Plus 4.5.1 software in digitalized microscopic images. For measurement of the cross-sectional area, 100 cells (per animal) from the left ventricular wall were randomly chosen and analyzed in hematoxylin staining. Bar. 50 μm. *p < 0.01 vs. control, #p < 0.05 vs. HF.