Fig. 6.

H₂O₂ or doxorubicin increase p21^Cip1/WAF1 protein in cardiomyocytes to reduce apoptosis. (A) and (B) Cardiomyocytes were exposed to 0.2 mM H₂O₂ [(A) and (B)] or to 0.4 mM doxorubicin (E) for the times indicated and total extracts [(A) and (D)] or nuclear and cytosolic extracts (B) immunoblotted with antibodies to p21^Cip1/WAF1. Representative immunoblots of at least 4 independent experiments are shown. Densitometric analysis is included to the right panels (A) and (D). Results are means ± SEM (n = 4 independent myocyte preparations). *p < .05, **p < .01 relative to unstimulated cells (one-way ANOVA with Dunnett's post-test). (C) Cardiomyocytes were exposed to the concentrations of H₂O₂ indicated for 120 min and immunoblotted with antibodies to to p21^Cip1/WAF1. Densitometric analysis is included below the panel. Results are means ± SEM (n = 4 independent myocyte preparations). *p < .05, ****p < .0001 relative to unstimulated cells (one-way ANOVA with Dunnett's post-test). (D) and (F), Cardiomyocytes were exposed to 0.2 mM H₂O₂ (4 h) or 0.4 mM doxorubicin (4 h) alone (Control), following treatment with transfection reagent without oligodeoxynucleotides (no ODN) or following transfection with antisense ODNs (AS-ODNs) for Cdkn1a or scrambled ODNs (Scr-ODNs). Samples were immunoblotted with antibodies to p21^Cip1/WAF1, cleaved caspase 3 or the loading control sarcomeric α-actin. Representative immunoblots are shown on the left, with densitometric analysis on the right. Data are means ± SEM (n = 6 independent myocyte preparations). *p < .05, ****p < .0001 relative to vehicle, #p < .01 relative to H₂O₂ treated cells with no ODNs, @ p < .05 relative to Cdkn1a-AS-ODN (two-way ANOVA with Tukey post-test).