Fig. 2

Progressive myocardial hypertrophy, fibrosis and capillary rarefaction were observed in the RV from PAB rats. (A) Hematoxylin-eosin (HE) staining reveals larger cross-sectional area of cardiomyocytes in the RV from PAB rats (left); quantification of RV cross-sectional area of cardiomyocytes in PAB and sham rats at different time points (right). (B) The PAB rats demonstrate significant RV fibrosis starting from 2 weeks after surgery by Masson’s trichrome staining (left); quantification of RV fibrosis area in rats (right). (C)-(D) Compared with sham group, ANP and BNP expression in RV tissue of PAB rats were elevated and reach the peak at 4 weeks post-PAB by qPCR. (E)-(F) Fibrosis markers (Col1a1 and Col3a1) were increased in the RV of PAB rats and reach the peak at week 2 after surgery by qPCR. (G) Representative figures of CD31 immunofluorescence in RV (left), CD31(red) = platelet endothelial cell adhesion molecule; DAPI (blue) = 4′,6-diamidino-2-phenylindole. Quantitative analysis of RV capillary density (right). RV capillaries in PAB were decreased gradually from week 2 to 8 after surgery. (n = 5–7/group). ns = not significant, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, compared with sham group. # p < 0.05, ## p < 0.01, ### p < 0.001, compared with the indicated time point in PAB group. bar = 50 μm for HE and Masson’s trichrome staining, bar = 20 μm for CD31 immunofluorescence staining. ANP = atrial natriuretic peptide, BNP = brain natriuretic peptide, Col1a1 = collagen 1a1, Col3a1 = collagen 3a1, PAB = pulmonary artery banding group, sham = sham group