The TGFB1-TGFBR1 axis in rats after MI. 17 rats were subjected to MI through permanent ligation of the LAD coronary artery. 4 rats were sham-operated. Rats were assessed by PET to determine LV volumes and EF 48 hours and 2 months after ligation. Rats were sacrificed after 2 days (n = 3), 2 weeks (n = 3) or 2 months (n = 11). At sacrifice, hearts were harvested. (A) Total TGFB1 measured by ELISA in cardiac samples is up-regulated 2 months after MI. Data are expressed in pg of TGFB1 per μg of total cardiac proteins. Shown are mean ± 95% CI (n = 4 for sham, n = 11 for MI). (B) TGFB1 expression in the heart mildly correlates with 2-months EF. (C-D) TGFB1 expression correlates with the variations of LV end-diastolic and end-systolic volumes between 48 hours and 2 months. Correlation coefficients and P values are indicated. (E) Immunohistochemical analysis of TGFBR1 expression in cardiac slices. The technical control without anti TGFBR1 antibody attests for the specificity of the detection. TGFBR1 staining appears in red colour and nuclei appear in blue. TGFBR1 expression is up-regulated in the border zone of MI rats. Representative pictures of sham-operated rats (upper panels) and MI rats (lower panels) are shown. (F) TGFBR1 expression in the border zone 2 days and 2 weeks after MI. TGFBR1 expression is up-regulated in the border zone 2 weeks after MI. Representative pictures are shown. (G) Masson trichrome staining showing collagen deposition and fibrosis in the necrotic zone of the heart 2 months after MI. Representative pictures from a MI rat are shown.