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Figure 3 (A) Effect of antioxidants on myocyte apoptosis. Myocytes were treated with 10^–6 mol/l of doxorubicin in the presence or absence of either amlodipine (10^–6 mol/l), probucol (10^–5 to 10^–4 mol/l), ascorbic acid (5 x 10^–5 mol/l), or alpha-tocopherol (10^–4 mol/l) for 14 h. Fluorescent-stained nuclei of apoptotic myocytes were analyzed morphologically and expressed as the percentage of total nuclei, as described in the Methods section. Control myocytes were incubated in serum-deprived DMEM without any chemicals (n = 6). p < 0.0001 vs. control. p < 0.05 vs. doxorubicin. p < 0.0001 vs. doxorubicin. (B) Histochemical characterization of oxidative stress. 2',7'-Dichlorofluorescin diacetate (H₂DCFDA) was added to the cultures 1 h before the myocytes were treated with the chemicals listed subsequently for 14 h. Myocytes were examined as described in Methods. (a) Control cardiac myocytes; (b) 10^–6 mol/l of doxorubicin; (c) 10^–6 mol/l of doxorubicin in the presence of 10^–6 mol/l of amlodipine; (d) 10^–6 mol/l of doxorubicin in the presence of 10^–6 mol/l of nifedipine; (e) 10^–6 mol/l of doxorubicin in the presence of 10^–4 mol/l of probucol; (f) 10^–6 mol/l of doxorubicin in the presence of 5 x 10^–5 mol/l of ascorbic acid; (g) 10^–6 mol/l of doxorubicin in the presence of 10^–4 mol/l of alpha-tocopherol; and (h) 10^–6 mol/l of amlodipine alone. Photomicrographs are representative of at least three experiments for each experiment (magnification x 200).