Mitoquinone Prevents Cardiac Dysfunction by Normalizing Mitochondrial ROS and Calcium Handling in Acute Myocardial Infarction

Figures

• 

  FIGURE 1. Effects of MitoQ on physiological and cellular parameters in a 7‐day myocardial infarction (MI) model. The following groups were analyzed: Sham, Sham MitoQ, MI, and MI MitoQ. (A) Body weight gain; (B) infarct size; (C) left ventricle‐to‐body weight ratio (LV/BW); (D) right ventricle‐to‐body weight ratio (RV/BW); (E) lung wet weight‐to‐body weight ratio (LW/BW); (F) collagen content in the left ventricle (LV); (G) interstitial collagen analysis in the LV assessed by Picrosirius Red staining; Scale = 50 μm; (H) representative images of isolated cardiomyocytes, Scale = 20 μm; (I) cell area; (J) cell length; (K) cell width. Data are presented as mean ± SEM. Statistical analysis was performed using two‐way ANOVA. *p < 0.05 vs. Sham; #p < 0.05 vs. MI; @ p < 0.05 vs. Sham MitoQ; ns, not significant. The number of animals per group is indicated in parentheses.

• 

  FIGURE 2. Impact of MitoQ treatment on hemodynamic and contractile parameters in rats following myocardial infarction (MI). (A) Both systolic pressure (SBP); (B) diastolic blood pressure (DBP); (C) left ventricular systolic pressure (LVSP); (D) left ventricular end‐diastolic pressure (LVEDP); (E) maximum rates of pressure development (+dP/dt_max); (F) minimum rates of pressure development; (G) isometric force (g/g) in the left ventricular papillary muscles at baseline (CaCl2 1.25 mM); (H) positive first‐time derivative (dF/dt+); (I) negative first‐time derivative (dF/dt‐); (J) post‐rest potentiation (15, 30, and 60 s) (g/mg); (K) isometric force (g/g) in the left ventricular papillary muscles measured with different extracellular CaCl2 concentrations (0.62, 1.25, 2.5, and 3.75 mM). (L) Isometric force (g/g) in the left ventricular papillary muscles measured in response to different isoproterenol concentrations (10−7 to 10−2 M) in 0.62 mM calcium. Data are presented as mean ± SEM. Statistical analysis was performed using two‐way ANOVA. *p < 0.05 vs. Sham; #p < 0.05 vs. MI; @p < 0.05 vs. Sham MitoQ; ns not significant; &p < 0.05 vs. 10−10M. The number of animals per group is indicated in…

• 

  FIGURE 3. Effects of MitoQ on contraction and relaxation kinetics in isolated cardiomyocytes. (A) Overall contraction‐relaxation time (CRT); (B) contraction time (CT); (C) relaxation time (RT); (D) contraction‐relaxation time to 90% relaxation (CRT‐90). (E) time required to reach 90% relaxation (RT‐T90); (F) time from peak contraction to 90% of baseline (RTPB‐T90). Data are presented as mean ± SEM. Statistical analysis was performed using two‐way ANOVA. *p < 0.05 vs. Sham; #p < 0.05 vs. MI; ns, not significant. The number of animals per group is indicated in parentheses.

• 

  FIGURE 4. Evaluation of the effects of 7 days of treatment with MitoQ on the contractile mechanics of isolated cardiomyocytes. (A) Maximum contraction speed (μm/s); (B) maximum relaxation speed (μm/s); (C) shortening area (μm2). Data are presented as mean ± SEM. Statistical analysis was performed using two‐way ANOVA. *p < 0.05 vs. Sham; #p < 0.05 vs. MI; ns not significant. The number of animals per group is indicated in parentheses.

• 

  FIGURE 5. Treatment with MitoQ prevents contractile changes in isolated cardiomyocytes from rats subjected to 7 days post‐infarction. (A) Representative images of Ca2+ transient fluorescence, Scale = 20 μm; (B) representative trace of Ca2+ transient; (C) amplitude of Ca2+ transient; (D) time to 50% decay of Ca2+ transient. Approximately 20 cells per animal were analyzed. Data are presented as mean ± SEM. Statistical analysis was performed using two‐way ANOVA. *p < 0.05 vs. Sham; #p < 0.05 vs. MI; ns, not significant. The number of animals per group is indicated in parentheses.

• 

  FIGURE 6. Effects of MitoQ treatment on the expression of proteins related to calcium handling in the myocardium post‐myocardial infarction (MI). (A) Western blot for sarcoplasmic reticulum Ca2 + ‐ATPase (SERCA2a) protein expression in left ventricular tissue; (B) Western blot for phospholamban (PLN) protein expression in left ventricular tissue; (C) phosphorylation of PLN at serine 16 (pPLN Ser16); (D) phosphorylation of PLN at threonine 17 (pPLN Thr17). Protein expression was normalized to total protein. Representative images are shown above for all analyses. Data are presented as mean ± SEM. Statistical analysis was performed using two‐way ANOVA. Differences were considered significant at p < 0.05. The number of animals per group is indicated in parentheses.

• 

  FIGURE 7. Effects of MitoQ treatment on mitochondrial superoxide (O2 •−) production in cardiomyocytes after myocardial infarction (MI). (A) Representative images stained with MitoSOX, a fluorescent indicator for mitochondrial superoxide. Scale = 20 μm; (B) quantitative analysis of MitoSOX fluorescence; (C) representative images of myocardial tissue sections stained with dihydroethidium (DHE), a fluorescent probe used to assess reactive oxygen species (ROS) production. Scale = 25 μm. (D) Quantitative analysis of DHE fluorescence intensity. Data are presented as mean ± SEM. Statistical analysis was performed using two‐way ANOVA. *p < 0.05 vs. Sham; #p < 0.05 vs. MI. The number of animals per group is indicated in parentheses.

• 

  FIGURE 8. Effects of MitoQ on the expression of enzymes related to oxidative stress in myocardial tissue following myocardial infarction (MI). (A) Western blot for NOX‐1 protein expression in left ventricular tissue; (B) Western blot for NOX‐2 protein expression in left ventricular tissue; (C) Western blot for NOX‐4 protein expression in left ventricular tissue; (D) Western blot for SOD‐1 protein expression in left ventricular tissue; (E) Western blot for SOD‐2 protein expression in left ventricular tissue; (F) Western blot for Catalase protein expression in left ventricular tissue. Protein expression was normalized to total protein. Representative images are shown above for all analyses. Data are presented as mean ± SEM. *p < 0.05 vs. Sham. Statistical analysis was performed using two‐way ANOVA. Differences were considered significant at p < 0.05. The number of animals per group is indicated in parentheses.