scholarly journals Mitochondrial respiration and H2O2 emission in saponin-permeabilized murine diaphragm fibers: optimization of fiber separation and comparison to limb muscle

2019 ◽  
Vol 317 (4) ◽  
pp. C665-C673
Author(s):  
Dongwoo Hahn ◽  
Ravi A. Kumar ◽  
Terence E. Ryan ◽  
Leonardo F. Ferreira
Keyword(s):  
Mitochondrial Respiration ◽  
Citrate Synthase ◽  
Limb Muscle ◽  
Mitochondrial Content ◽  
New Approach ◽  
Disease States ◽  
Fiber Separation ◽  
Mouse Diaphragm ◽  
Permeabilized Fibers ◽  
Permeabilized Muscle

Diaphragm abnormalities in aging or chronic diseases include impaired mitochondrial respiration and H2O2 emission, which can be measured using saponin-permeabilized muscle fibers. Mouse diaphragm presents a challenge for isolation of fibers due to relatively high abundance of connective tissue in healthy muscle that is exacerbated in disease states. We tested a new approach to process mouse diaphragm for assessment of intact mitochondria respiration and ROS emission in saponin-permeabilized fibers. We used the red gastrocnemius (RG) as “standard” limb muscle. Markers of mitochondrial content were two– to fourfold higher in diaphragm (Dia) than in RG ( P < 0.05). Maximal O2 consumption ( JO2: pmol·s−1·mg−1) in Dia was higher with glutamate, malate, and succinate (Dia 399 ± 127, RG 148 ± 60; P < 0.05) and palmitoyl-CoA + carnitine (Dia 15 ± 5, RG 7 ± 1; P < 0.05) than in RG, but not different between muscles when JO2 was normalized to citrate synthase activity. Absolute JO2 for Dia was two– to fourfold higher than reported in previous studies. Mitochondrial JH2O2 was higher in Dia than in RG ( P < 0.05), but lower in Dia than in RG when JH2O2 was normalized to citrate synthase activity. Our findings are consistent with an optimized diaphragm preparation for assessment of intact mitochondria in permeabilized fiber bundles. The data also suggest that higher mitochondrial content potentially makes the diaphragm more susceptible to “mitochondrial onset” myopathy. Overall, the new approach will facilitate testing and understanding of diaphragm mitochondrial function in mouse models that are used to advance biomedical research and human health.

scholarly journals Methodological considerations when assessing mitochondrial respiration and biomarkers for mitochondrial content in human skeletal muscle

2021 ◽  
Author(s):  
Jujiao Kuang ◽  
Nicholas J Saner ◽  
Javier Botella ◽  
Matthew J-C Lee ◽  
Cesare Granata ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Mitochondrial Respiration ◽  
Coefficient Of Variation ◽  
Human Skeletal Muscle ◽  
Citrate Synthase ◽  
Membrane Integrity ◽  
Mitochondrial Outer Membrane ◽  
Muscle Fibres ◽  
Biological Variability ◽  
Mitochondrial Content

Background: The assessment of mitochondrial respiration and mitochondrial content are two common measurements in the fields of skeletal muscle research and exercise science. However, to verify the validity of the observed changes in both mitochondrial respiration and mitochondrial content following an intervention such as exercise training, it is important to determine the reliability and reproducibility of the experimental design and/or techniques employed. We examined the repeatability of widely used methodologies for assessing mitochondrial respiration and mitochondrial content, respectively; the measurement of maximal mitochondrial oxidative phosphorylation in permeabilized muscle fibres using high-resolution respirometry, and the measurement of citrate synthase activity as a biomarker for mitochondrial content in a microplate with spectrophotometer. Result: For mitochondrial respiration, the coefficient of variation for repeated measurements using muscle sampled from same biopsy decreased from 12.7% to 11% when measured in triplicate with outliers excluded, rather than in duplicate. The coefficient of variation was 9.7% for repeated muscle biopsies sampled across two separated days. For measurements of citrate synthase activity, the coefficient of variation was 3.5% of three technical repeats on the same plate, 10.2% for duplicate analyses using the same muscle lysate when conducted in the same day, and 30.5% when conducted four weeks apart. Conclusion: We have provided evidence for important technical considerations when measuring mitochondrial respiration with human skeletal muscle: 1) the relatively large technical variability can be reduced by increasing technical repeats and excluding outliers; 2) the biological variability and absolute mitochondrial respiration value of the participants should be considered when estimating the required sample size; 3) a new threshold of 15% for the increase in respiration rate after the addition of cytochrome c test for testing mitochondrial outer membrane integrity. When analysing citrate synthase activity, our evidence suggests it is important to consider the following: 1) all samples from the same study should be homogenized and measured at the same time using the same batch of freshly made chemical reagents; 2) biological variability should be considered when detecting small change in mitochondrial content; 3) the relative change should be used to compare the outcomes from different studies.

scholarly journals Cardiac, skeletal, and smooth muscle mitochondrial respiration: are all mitochondria created equal?

2014 ◽  
Vol 307 (3) ◽  
pp. H346-H352 ◽  
Author(s):  
Song-Young Park ◽  
Jayson R. Gifford ◽  
Robert H. I. Andtbacka ◽  
Joel D. Trinity ◽  
John R. Hyngstrom ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Oxidative Phosphorylation ◽  
Mitochondrial Respiration ◽  
Complex I ◽  
Citrate Synthase ◽  
Smooth Muscles ◽  
Respiratory Control ◽  
Respiratory Control Ratio ◽  
Mitochondrial Content ◽  
Healthy Human

Unlike cardiac and skeletal muscle, little is known about vascular smooth muscle mitochondrial respiration. Therefore, the present study examined mitochondrial respiratory rates in smooth muscle of healthy human feed arteries and compared with that of healthy cardiac and skeletal muscles. Cardiac, skeletal, and smooth muscles were harvested from a total of 22 subjects (53 ± 6 yr), and mitochondrial respiration was assessed in permeabilized fibers. Complex I + II, state 3 respiration, an index of oxidative phosphorylation capacity, fell progressively from cardiac to skeletal to smooth muscles (54 ± 1, 39 ± 4, and 15 ± 1 pmol·s−1·mg−1, P < 0.05, respectively). Citrate synthase (CS) activity, an index of mitochondrial density, also fell progressively from cardiac to skeletal to smooth muscles (222 ± 13, 115 ± 2, and 48 ± 2 μmol·g−1·min−1, P < 0.05, respectively). Thus, when respiration rates were normalized by CS (respiration per mitochondrial content), oxidative phosphorylation capacity was no longer different between the three muscle types. Interestingly, complex I state 2 normalized for CS activity, an index of nonphosphorylating respiration per mitochondrial content, increased progressively from cardiac to skeletal to smooth muscles, such that the respiratory control ratio, state 3/state 2 respiration, fell progressively from cardiac to skeletal to smooth muscles (5.3 ± 0.7, 3.2 ± 0.4, and 1.6 ± 0.3 pmol·s−1·mg−1, P < 0.05, respectively). Thus, although oxidative phosphorylation capacity per mitochondrial content in cardiac, skeletal, and smooth muscles suggest all mitochondria are created equal, the contrasting respiratory control ratio and nonphosphorylating respiration highlight the existence of intrinsic functional differences between these muscle mitochondria. This likely influences the efficiency of oxidative phosphorylation and could potentially alter ROS production.

Curcumin induces mitochondrial biogenesis by increasing cAMP levels via PDE4A inhibition in skeletal muscle

2021 ◽  
pp. 1-34
Author(s):  
Hamidie Ronald D Ray ◽  
Tsubasa Shibaguchi ◽  
Tatsuya Yamada ◽  
Rikuhide Koma ◽  
Rie Ishizawa ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Mitochondrial Biogenesis ◽  
Mitochondrial Respiration ◽  
Citrate Synthase ◽  
Signalling Pathway ◽  
Curcumin Treatment ◽  
Camp Content ◽  
Signalling Molecules ◽  
Camp Levels

Abstract Background: Previous research has suggested that curcumin potentially induces mitochondrial biogenesis in skeletal muscle via increasing cAMP levels. However, the regulatory mechanisms for this phenomenon remain unknown. The purpose of the present study was to clarify the mechanism by which curcumin activates cAMP-related signalling pathways that upregulate mitochondrial biogenesis and respiration in skeletal muscle. Methods: The effect of curcumin treatment (i.p., 100 mg/kg-BW/day for 28 days) on mitochondrial biogenesis was determined in rats. The effects of curcumin and exercise (swimming for 2 h/day for 3 days) on the cAMP signalling pathway were determined in the absence and presence of phosphodiesterase (PDE) or protein kinase A (PKA) inhibitors. Mitochondrial respiration, citrate synthase (CS) activity, cAMP content, and protein expression of cAMP/PKA signalling molecules were analysed. Results: Curcumin administration increased COX-IV protein expression, and CS and complex I activity, consistent with the induction of mitochondrial biogenesis by curcumin. Mitochondrial respiration was not altered by curcumin treatment. Curcumin and PDE inhibition tended to increase cAMP levels with or without exercise. In addition, exercise increased the phosphorylation of PDE4A, whereas curcumin treatment strongly inhibited PDE4A phosphorylation regardless of exercise. Furthermore, curcumin promoted AMPK phosphorylation and PGC-1α deacetylation. Inhibition of PKA abolished the phosphorylation of AMPK. Conclusion: The present results suggest that curcumin increases cAMP levels via inhibition of PDE4A phosphorylation, which induces mitochondrial biogenesis through a cAMP/PKA/AMPK signalling pathway. Our data also suggest the possibility that curcumin utilizes a regulatory mechanism for mitochondrial biogenesis that is distinct from the exercise-induced mechanism in skeletal muscle.

scholarly journals Exercise training enhances white adipose tissue metabolism in rats selectively bred for low- or high-endurance running capacity

2013 ◽  
Vol 305 (3) ◽  
pp. E429-E438 ◽  
Author(s):  
Erin J. Stephenson ◽  
Sarah J. Lessard ◽  
Donato A. Rivas ◽  
Matthew J. Watt ◽  
Ben B. Yaspelkis ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Exercise Training ◽  
White Adipose Tissue ◽  
Citrate Synthase ◽  
Mitochondrial Protein ◽  
Treadmill Running ◽  
Endurance Running ◽  
Insulin Resistant ◽  
Disease States ◽  
Hcr Model

Impaired visceral white adipose tissue (WAT) metabolism has been implicated in the pathogenesis of several lifestyle-related disease states, with diminished expression of several WAT mitochondrial genes reported in both insulin-resistant humans and rodents. We have used rat models selectively bred for low- (LCR) or high-intrinsic running capacity (HCR) that present simultaneously with divergent metabolic phenotypes to test the hypothesis that oxidative enzyme expression is reduced in epididymal WAT from LCR animals. Based on this assumption, we further hypothesized that short-term exercise training (6 wk of treadmill running) would ameliorate this deficit. Approximately 22-wk-old rats (generation 22) were studied. In untrained rats, the abundance of mitochondrial respiratory complexes I–V, citrate synthase (CS), and PGC-1 was similar for both phenotypes, although CS activity was greater than 50% in HCR ( P = 0.09). Exercise training increased CS activity in both phenotypes but did not alter mitochondrial protein content. Training increased the expression and phosphorylation of proteins with roles in β-adrenergic signaling, including β3-adrenergic receptor (16% increase in LCR; P < 0.05), NOR1 (24% decrease in LCR, 21% decrease in HCR; P < 0.05), phospho-ATGL (25% increase in HCR; P < 0.05), perilipin (25% increase in HCR; P < 0.05), CGI-58 (15% increase in LCR; P < 0.05), and GLUT4 (16% increase in HCR; P < 0.0001). A training effect was also observed for phospho-p38 MAPK (12% decrease in LCR, 20% decrease in HCR; P < 0.05) and phospho-JNK (29% increase in LCR, 20% increase in HCR; P < 0.05). We conclude that in the LCR-HCR model system, mitochondrial protein expression in WAT is not affected by intrinsic running capacity or exercise training. However, training does induce alterations in the activity and expression of several proteins that are essential to the intracellular regulation of WAT metabolism.

Abstract 438: Hydrogen Sulfide Promotes Mitochondrial Biogenesis Through the Regulation of AMP-activated Protein Kinase

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Yuuki Shimizu ◽  
Rohini Polavarapu ◽  
John Calvert
Keyword(s):  
Hydrogen Sulfide ◽  
Mitochondrial Biogenesis ◽  
Target Genes ◽  
Nuclear Dna ◽  
Citrate Synthase ◽  
Serine Phosphorylation ◽  
Signaling Cascade ◽  
Disease States ◽  
Upstream Kinase ◽  
High Concentrations

Background: Hydrogen sulfide (H 2 S) possesses numerous cellular actions that account for its cardioprotective effects. A mechanism of particular interest is its effects on the mitochondria. At low concentrations, H 2 S donates electrons to the electron transport chain, whereas at high concentrations it inhibits mitochondrial respiration. H 2 S therapy improves mitochondrial function and prevents the loss of mitochondria following the onset of myocardial ischemia. However, it is not known if these improvements are associated with simply a reduction in injury or if mitochondrial biogenesis is involved. Therefore, the purpose of this study was to determine if H 2 S regulates/induces mitochondrial biogenesis in the heart. Methods and Results: C57BL/6J mice (8 weeks of age) were given an orally active H 2 S donor (SG-1002; 20 mg/kg/day) in their chow for 4 weeks. For these studies we focused our analysis on an AMPK-PGC1α signaling cascade. SG-1002 significantly increased the phosphorylation of AMPK, the serine phosphorylation of PGC1α, and increased the nuclear localization of PGC1α. This was associated with an increase in the gene expression of PGC1α target genes associated with mitochondrial biogenesis, an increase in mitochondrial to nuclear DNA ratios and an increase in citrate synthase activity. SG-1002 failed to elicit these changes in AMPK deficient mice. Therefore, we sought to determine how SG-1002 activated AMPK. SG-1002 did not alter the phosphorylation of LKB1, an upstream kinase of AMPK, and did not alter the levels of AMP (activator of AMPK). SG-1002 did not alter the expression of protein phosphatase 2A (PP2A; dephosphorylates AMPK), but it did significantly decrease the activity of PP2A). This decrease was accompanied by an increase in the sulfhydration of PP2A, suggesting that this modification is inhibitory. Conclusion: These data suggest that H 2 S augments mitochondrial biogenesis in the heart via an AMPK-PGC1α signaling cascade. This is important because mitochondrial abnormalities are associated with a number of disease states (diabetes and heart failure) where H 2 S levels are decreased. Therefore, strategies aimed at increasing H 2 S levels could potentially induce the generation of new, healthy mitochondria.

Physiological diversity of mitochondrial oxidative phosphorylation

2006 ◽  
Vol 291 (6) ◽  
pp. C1172-C1182 ◽  
Author(s):  
G. Benard ◽  
B. Faustin ◽  
E. Passerieux ◽  
A. Galinier ◽  
C. Rocher ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Respiratory Chain ◽  
Citrate Synthase ◽  
Intrinsic Activity ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Respiratory Chain Complexes ◽  
Mitochondrial Content ◽  
Physiological Diversity ◽  
Chain Complexes ◽  
Functional Features

To investigate the physiological diversity in the regulation and control of mitochondrial oxidative phosphorylation, we determined the composition and functional features of the respiratory chain in muscle, heart, liver, kidney, and brain. First, we observed important variations in mitochondrial content and infrastructure via electron micrographs of the different tissue sections. Analyses of respiratory chain enzyme content by Western blot also showed large differences between tissues, in good correlation with the expression level of mitochondrial transcription factor A and the activity of citrate synthase. On the isolated mitochondria, we observed a conserved molar ratio between the respiratory chain complexes and a variable stoichiometry for coenzyme Q and cytochrome c, with typical values of [1–1.5]:[30–135]:[3]:[9–35]:[6.5–7.5] for complex II:coenzyme Q:complex III:cytochrome c:complex IV in the different tissues. The functional analysis revealed important differences in maximal velocities of respiratory chain complexes, with higher values in heart. However, calculation of the catalytic constants showed that brain contained the more active enzyme complexes. Hence, our study demonstrates that, in tissues, oxidative phosphorylation capacity is highly variable and diverse, as determined by different combinations of 1) the mitochondrial content, 2) the amount of respiratory chain complexes, and 3) their intrinsic activity. In all tissues, there was a large excess of enzyme capacity and intermediate substrate concentration, compared with what is required for state 3 respiration. To conclude, we submitted our data to a principal component analysis that revealed three groups of tissues: muscle and heart, brain, and liver and kidney.

Decreased muscle ACE activity enhances functional response to endurance training in rats, without change in muscle oxidative capacity or contractile phenotype

2009 ◽  
Vol 107 (1) ◽  
pp. 346-353 ◽  
Author(s):  
Estelle Habouzit ◽  
Hélène Richard ◽  
Hervé Sanchez ◽  
Nathalie Koulmann ◽  
Bernard Serrurier ◽  
...  
Keyword(s):  
Ace Inhibitor ◽  
Citrate Synthase ◽  
Ace Inhibition ◽  
Oxidative Capacity ◽  
Time To Exhaustion ◽  
Metabolic Efficiency ◽  
Endurance Time ◽  
Female Wistar Rats ◽  
Permeabilized Fibers ◽  
Training Protocol

In the present study, we tested the hypothesis that chronic ANG I-converting enzyme (ACE) inhibition could improve the training-induced improvement in endurance exercise performance and that this could be related to enhanced skeletal muscle metabolic efficiency. Female Wistar rats were assigned to four groups comprising animals either maintained sedentary or endurance trained (Sed and Tr, respectively), and treated or not for 10 wk with an ACE inhibitor, perindopril (2 mg·kg−1·day−1) (Per and Ct, respectively) ( n = 8 each). Trained rats underwent an 8-wk treadmill training protocol that consisted of 2 h/day running at 30 m/min on a 8% decline. Before the start of and 1 wk before the end of experimental conditioning, the running time to exhaustion of rats was measured on a treadmill. The training program led to an increase in endurance time, higher in Tr-Per than in Tr-Ct group (125% in Tr-Ct vs. 183% in Tr-Per groups, P < 0.05). Oxidative capacity, measured in saponin-permeabilized fibers of slow soleus and fast plantaris muscles, increased with training, but less in Tr-Per than in Tr-Ct rats. The training-induced increase in citrate synthase activity also was less in soleus from Tr-Per than Tr-Ct rats. The training-induced increase in the percentage of the type IIa isoform of myosin heavy chain (MHC) (45%, P < 0.05) and type IIx MHC (25%, P < 0.05) associated with decreased type IIb MHC (34%, P < 0.05) was minimized by perindopril administration. These findings demonstrate that the enhancement in physical performance observed in perindopril-treated animals cannot be explained by changes in mitochondrial respiration and/or MHC distribution within muscles involved in running exercise.

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