Figure 3. EPO inhibits cardiomyocyte apoptosis in infarcted hearts.

(A) TUNEL staining (brown) of infarcted hearts from WT mice 24 hours after ligation. Scale bars: 100 μm. The number of TUNEL-positive cardiomyocytes in the border area was counted. *P < 0.01 (n = 10). (B) Representative Western blots of cleaved caspase-3 (cl. caspase-3) protein in the heart 24 hours after MI are shown (n = 4). (C) Detection of apoptotic cardiomyocytes using FITC-labeled TUNEL staining (green). Nuclei were counterstained with Hoechst 33258 (blue). The TUNEL-positive cardiomyocytes were counted (n = 10). *P < 0.05. (D) Samples were pretreated with EPO for 8 hours before H₂O₂ treatment, and the expression of Bcl-2 and cleaved caspase-3 24 hours after H₂O₂ treatment was analyzed by Western blotting. Representative results from 3 experiments are shown. (E) Detection of apoptotic cardiomyocytes using Cy-3–labeled annexin V staining (red). Nuclei were counterstained with Hoechst 33258 (blue). Cardiomyocytes were infected with adenoviral vectors encoding dominant negative form of EPOR or LacZ at 10 MOI. The number of annexin V–positive cardiomyocytes was counted (n = 10). *P < 0.05.