MitoQ improves mitochondrial dysfunction in heart failure induced by pressure overload

Figures

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  Fig. 1. MitoQ restores mitochondrial membrane potential, decreases size and internal complexity in subsarcolemmal mitochondria in heart failure after 14 weeks of transverse aortic constriction. Changes in mitochondrial yield, membrane potential, size and internal complexity in SHAM, TAC and TAC plus MitoQ. N - Number of animals used. *p < .05 compared to SHAM. #p < .05 compared to TAC. Results are expressed as the means ± SEM. Differences were analyzed using one-way ANOVA followed by a post hoc Fischer test. (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.)

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  Fig. 2. MitoQ restores mitochondrial dysfunction in IFM and SSM in heart failure induced by pressure overload after 14 weeks of transverse aortic constriction. Mitochondrial subpopulations respiration. Individual mitochondrial subpopulations were isolated from SHAM, TAC and TAC plus MitoQ hearts, and polarographic measurements were performed to index oxygen consumption under state 3 and 4 respiration conditions. Respiration of individual electron transport chain (ETC) complex was defined as the rate of oxygen consumed in the presence of specific substrate (glutamate and malate) for complex I. All respiration rates are expressed in Atoms O.mg mitochondrial protein-1 min−1. RCR (respiratory control ratio, state 3/state 4) and the ratio of ADP:O in isolated subsarcolemmal and Intermyofibrillar mitochondria. Number of animals used 13–15 per group. *p < .05 compared to SHAM. #p < .05 compared to TAC. Results are expressed as the means ± SEM. Differences were analyzed using one-way ANOVA followed by a post hoc Fischer test.

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  Fig. 3. MitoQ restores β-oxidation in subsarcolemmal mitochondria from heart failure induced by pressure overload after 14 weeks of transverse aortic constriction. Mitochondrial subpopulations respiration. Individual mitochondrial subpopulations were isolated from SHAM, TAC and TAC plus MitoQ hearts, and polarographic measurements were performed to index oxygen consumption under state 3 and 4 respiration conditions. Respiration of individual electron transport chain (ETC) complex was defined as the rate of oxygen consumed in the presence of specific substrate (Palmitoyl-carnitine) for β-oxidation. All respiration rates are expressed in Atoms O.mg mitochondrial protein-1 min−1, RCR (respiratory control ratio, state 3/state 4) and the ratio of ADP:O in isolated subsarcolemmal and Intermyofibrillar mitochondria. Number of animals used 13–15 per group. *p < .05 compared to SHAM. #p < .05 compared to TAC. Results are expressed as the means ± SEM. Differences were analyzed using one-way ANOVA followed by a post hoc Fischer test.

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  Fig. 4. MitoQ restores the increase in state 4 in intermyofibrillar mitochondria from heart failure induced by pressure overload after 14 weeks of transverse aortic constriction. Mitochondrial subpopulations respiration. Individual mitochondrial subpopulations were isolated from SHAM, TAC and TAC plus MitoQ hearts, and polarographic measurements were performed to index oxygen consumption under state 3 and 4 respiration conditions. Respiration of individual electron transport chain (ETC) complex was defined as the rate of oxygen consumed in the presence of specific substrate (succinate + rotenone) for complex II. All respiration rates are expressed in Atoms O.mg mitochondrial protein-1 min−1, RCR (respiratory control ratio, state 3/state 4) and the ratio of ADP:O in isolated subsarcolemmal and Intermyofibrillar mitochondria. Number of animals used 13–15 per group. *p < .05 compared to SHAM. #p < .05 compared to TAC. Results are expressed as the means ± SEM. Differences were analyzed using one-way ANOVA followed by a post hoc Fischer test.

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  Fig. 5. Heart failure decreases myocardial activity of mitochondrial function and the fatty acid oxidation pathway. Myocardial activity of citrate synthase (CS), medium chain acyl-CoA dehydrogenase (MCAD) (B) and aconitase (C). Activity of citrate synthase (CS) (D), medium chain acyl-CoA dehydrogenase (MCAD) (E) and aconitase (F) in the intermyofibrillar mitochondria. Activity of citrate synthase (CS) (G), medium chain acyl-CoA dehydrogenase (MCAD) (H) and aconitase (I) in the subsarcolemmal mitochondria. Individual mitochondrial subpopulations were isolated from SHAM, TAC and TAC plus MitoQ hearts. Number of animals used 13–15 per group. *p < .05 compared to SHAM. #p < .05 compared to TAC. Results are expressed as the means ± SEM. Differences were analyzed using one-way ANOVA followed by a post hoc Fischer test.

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  Fig. 6. MitoQ restores hydrogen peroxide production in intermyofibrillar and subsarcolemmal mitochondria from heart failure induced by pressure overload after 14 weeks of transverse aortic constriction. Hydrogen peroxide production in intermyofibrillar and subsarcolemmal mitochondria from individual mitochondrial subpopulations isolated from SHAM, TAC and TAC plus MitoQ hearts. Two different substrates were used to assess hydrogen peroxide production from complex I (glutamate + malate) and complex III (rotenone + succinate). Number of animals used is indicated in parenthesis. *p < .05 compared to SHAM. #p < .05 compared to TAC. Results are expressed as the means ± SEM. Differences were analyzed using two-way ANOVA followed by a post hoc Fischer test.

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  Fig. 7. Calcium-uptake capacity and reactive oxygen species (ROS) sensitivity of mitochondria isolated from SHAM, TAC and TAC plus MitoQ hearts. A: rate of Ca2+ uptake by interfibrillar mitochondria (IFM) is monitored as a decrease in fluorescence of the extra-mitochondrial Ca2+ indicator (CaGN-5N; 700 nM). B: decrease in CaGN-5N fluorescence over time due to the uptake of Ca2+ by subsarcolemmal mitochondria (SSM). C: IFM mitochondria were primed for mitochondrial permeability transition pore (MPTP) opening with a low concentration of Ca2+ (22.5 µM) and were subsequently exposed to increasingly higher doses of tBH. Mitochondrial Ca2+ release as a result of tBH-induced MPTP was monitored as an increase in CaGN-5N fluorescence. D: increase in CaGN-5N fluorescence due to tBH-induced MPTP opening in SSM. AU, arbitrary fluorescence units; tBH, tert-butyl-hydroxyperoxide.). Number of animals used is indicated in parenthesis. *p < .05 compared to SHAM. #p < .05 compared to TAC. Results are expressed as the means ± SEM. Differences were analyzed using two-way ANOVA followed by a post hoc Fischer test.

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  Fig. 8. MitoQ improves calcium-induced mitochondrial swelling in intermyofibrillar and subsarcolemmal mitochondria from heart failure induced by pressure overload after 14 weeks of transverse aortic constriction. (A) Total cardiac mitochondria were isolated from SHAM, TAC and TAC plus MitoQ hearts and exposed to 100 and 500 nM Ca2+/mg mitochondrial protein to induce swelling. The change in absorbance that occurs as a result of mitochondrial swelling is monitored over time at 540 nm and is expressed relative to the absorbance at the beginning of the assay. Number of animals used is indicated in parenthesis. *p < .05 compared to SHAM. #p < .05 compared to TAC. Results are expressed as the means ± SEM. Differences were analyzed using two-way ANOVA followed by a post hoc Fischer test.