Expression and effects of human Bcl-2 on cardiomyocytes from transgenic mice. (A) Western blot analysis of human Bcl-2 in heart lysates of naive Bcl-2 Tg (n = 2) and WT (n = 2) mice. Increased expression of human Bcl-2 was observed in the transgenic group. (B) Bcl-2 expression in cardiomyocytes. Heart sections were costained with antihuman Bcl-2 recognized by FITC-conjugated secondary antibody (green) and anti-α actinin recognized by Texas red–conjugated secondary antibody (red) antibodies. Sections were counterstained with 4,6-diamidino-2-phenylindole (DAPI, blue). Striations, within the cardiomyocyte, consistently displayed α-actinin staining throughout the entire cell. Human Bcl-2, located exclusively within the cytoplasm of the cardiomyocyte, was identified only in hearts from Bcl-2 Tg mice. A Leica DMRB fluorescent microscope (Leica Microsystems, Frankfurt, Germany) and SPOT Advanced Version 3.4.2 software (Diagnostic Instruments, Sterling Heights, MI) were used. Original magnification, × 400. (C) Effect of human Bcl-2 overexpression on cardiomyocyte survival. Cardiomyocytes from human Bcl-2 Tg (n = 3) and WT (n = 3) mice were cultured in the presence (i) or absence (ii) of 10% fetal calf serum. The percentage of surviving cells was assessed by the trypan blue exclusion assays at the indicated time points. Data are shown as the percentage of surviving cells against the number of initial plated cells and are representative of 2 independent experiments. Data are shown as mean ± SD. ^*P < .01.