Figure 5. ROS production is not increased in the cKO hearts.

(A) Measurement of H₂O₂ production using Amplex Red in isolated cardiac mitochondria from CON (white) and cKO (black) mice treated with pyruvate/malate (10/5 mM; P/M), succinate (10 mM; S), rotenone (10 μM; Rot), Antimicyn A (1 mg/ml; AntA), ADP (2.5 mM) or combinations of those (n=4) and (B) mitochondrial or cytosolic H₂O₂ production in isolated cardiomyocytes using a fluorescent probe targeted to mitochondria (Mito-Hyper) or to cytosol (Cyto-Hyper; n=27–43; *P<0.05 vs CON). (C) Data showing the change of MitoSOX fluorescence at 405 nm excitation during a 5 min period before (−) or after the addition of respiration substrates (P/M/ADP). Data are expressed as mean ± SEM (n=9–10 cells from 2–3 mice; ^#P<0.05 P/M/ADP vs. non-treated; *P< 0.05 cKO vs. CON). (D) Representative images of CON and cKO permeabilized cardiomyocytes showing the MitoSOX fluorescence at 5 min after the addition of respiration substrates (10 mM pyruvate, 5 mM malate and 2 mM ADP). (E) Cardiac tissue aconitase enzyme activity (n=3). Data are expressed as means ± SEM. (F) Representative western blot for mitochondrial catalase in hearts from CON, cKO and cKO/mCat mice. (G) Heart weight normalized to tibia length, (H) fractional shortening and (I) LV end-diastolic dimension at 4 weeks after TAC or sham surgery (n=11 for the cKO/mCat TAC group and n=5 for the rest of the groups). Data are expressed as means ± SEM. *P<0.05 vs the respective sham indicated by the dotted line and ^#P<0.05 vs CON-TAC.