scholarly journals Mitochondrial Function in Oxidative and Glycolytic Bovine Skeletal Muscle Postmortem

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
P. Ramos ◽  
L. Bell ◽  
S. Wohlgemuth ◽  
T. Scheffler
Keyword(s):  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Outer Membrane ◽  
Functional Properties ◽  
Mitochondrial Function ◽  
Complex I ◽  
Fixed Effects ◽  
Citrate Synthase ◽  
Electron Flow ◽  
Coupling Efficiency

ObjectivesMitochondrial function in postmortem muscle is affected by decreasing oxygenation. Functional properties relating to energy production and integrity of mitochondria may influence development of meat quality characteristics. Therefore, the objective was to evaluate changes in mitochondrial function in oxidative and glycolytic muscles during the first 24h postmortem.Materials and MethodsSteers (n = 6) of primarily Angus (80 to 100%) genetics were harvested at approximately 18.5 mo and 630 kg live weight. Samples from the longissimus lumborum (LL) and diaphragm (Dia) were collected at 1, 3, and 24h postmortem. Fresh-preserved muscle samples were permeabilized using saponin, and muscle bundles (2–4 mg) were transferred to a high-resolution oxygraph for respiration measurements (oxygen consumption rate, OCR, pmol/sec/mg of tissue). Samples were assessed in duplicate under hyperoxia. First, pyruvate and malate were added to support the TCA cycle and assess leak respiration. Then, ADP was added to support electron flow through complex I. The influence of glutamate on NADH production (complex I) was tested, followed by complex II activation by succinate. Integrity of the mitochondria outer membrane was tested with cytochrome c. Next, an uncoupler (FCCP) was added to force the electron transport system (ETS) to maximum capacity. Citrate synthase (CS) activity (nmol/min/mg tissue) was determined in frozen samples and used as a marker of mitochondria content. Subsequently, respiration data were normalized to CS activity (pmol/sec/U CS) to account for differences in mitochondria content. Coupling efficiency of oxidative phosphorylation was calculated as 1– (Leak/ADP-stimulated oxidative phosphorylation capacity). Raw and normalized OCR were analyzed in a randomized block design, with slaughter date as block and fixed effects of muscle, time, and the interaction. Time was considered a repeated measure.ResultsMuscle type affected (P = 0.0002) leak OCR, with Dia showing a higher rate than LL. After ADP was added, mitochondria from Dia exhibited higher OCR at all times tested and at all steps, with OCR being 4 times higher after FCCP addition. Mitochondrial content, evidenced by greater (P < 0.0001) CS activity in Dia, largely explained differences in OCR between muscles. After OCR was normalized to CS activity, the 1 and 3h postmortem OCR from Dia and LL were similar (P > 0.05). However, at 24h postmortem, OCR after ADP, glutamate, and FCCP additions were greater (P < 0.05) in Dia mitochondria. Time, but not muscle, affected cytochrome c response. At 1h postmortem, cytochrome c increased OCR by 6.6%, supporting that mitochondria outer membrane integrity is not compromised. However, cytochrome c response at 3h postmortem increased 52.4%, indicating outer membrane damage. Coupling efficiency is different between muscles (P = 0.005) with Dia exhibiting greater efficiency.ConclusionDespite inherent metabolic differences between the LL and Dia, mitochondria from both muscles are intact and coupled at 1h postmortem. However, by 24h postmortem, functional properties of LL mitochondria are reduced compared to Dia. Declining mitochondrial function may be associated with calcium overload, mitochondrial fragmentation, and protease activation.

Schisandrin Restores the Amyloid β-Induced Impairments on Mitochondrial Function, Energy Metabolism, Biogenesis, and Dynamics in Rat Primary Hippocampal Neurons

Pharmacology ◽  
2021 ◽  
pp. 1-11
Author(s):  
Zhongyuan Piao ◽  
Lin Song ◽  
Lifen Yao ◽  
Limei Zhang ◽  
Yichan Lu
Keyword(s):  
Energy Metabolism ◽  
Cytochrome C ◽  
Mitochondrial Biogenesis ◽  
Mitochondrial Function ◽  
Hippocampal Neurons ◽  
Citrate Synthase ◽  
Mitochondrial Permeability Transition ◽  
Amyloid Β ◽  
Mitochondrial Functions ◽  
Primary Hippocampal Neurons

Introduction: Schisandrin which is derived from Schisandra chinensis has shown multiple pharmacological effects on various diseases including Alzheimer’s disease (AD). It is demonstrated that mitochondrial dysfunction plays an essential role in the pathogenesis of neurodegenerative disorders. Objective: Our study aims to investigate the effects of schisandrin on mitochondrial functions and metabolisms in primary hippocampal neurons. Methods: In our study, rat primary hippocampal neurons were isolated and treated with indicated dose of amyloid β1–42 (Aβ1–42) oligomer to establish a cell model of AD in vitro. Schisandrin (2 μg/mL) was further subjected to test its effects on mitochondrial function, energy metabolism, mitochondrial biogenesis, and dynamics in the Aβ1–42 oligomer-treated neurons. Results and Conclusions: Our findings indicated that schisandrin significantly alleviated the Aβ1–42 oligomer-induced loss of mitochondrial membrane potential and impaired cytochrome c oxidase activity. Additionally, the opening of mitochondrial permeability transition pore and release of cytochrome c were highly restricted with schisandrin treatment. Alterations in cell viability, ATP production, citrate synthase activity, and the expressions of glycolysis-related enzymes demonstrated the relief of defective energy metabolism in Aβ-treated neurons after the treatment of schisandrin. For mitochondrial biogenesis, elevated expression of peroxisome proliferator-activated receptor γ coactivator along with promoted mitochondrial mass was found in schisandrin-treated cells. The imbalance in the cycle of fusion and fission was also remarkably restored by schisandrin. In summary, this study provides novel mechanisms for the protective effect of schisandrin on mitochondria-related functions.

scholarly journals Differential Effects of Silibinin A on Mitochondrial Function in Neuronal PC12 and HepG2 Liver Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Carsten Esselun ◽  
Bastian Bruns ◽  
Stephanie Hagl ◽  
Rekha Grewal ◽  
Gunter P. Eckert
Keyword(s):  
Membrane Potential ◽  
Oxidative Phosphorylation ◽  
Mitochondrial Membrane Potential ◽  
Cell Lines ◽  
Mitochondrial Function ◽  
Mitochondrial Membrane ◽  
Nitrosative Stress ◽  
Citrate Synthase ◽  
Atp Levels ◽  
Age Related

The Mediterranean plant Silybum marianum L., commonly known as milk thistle, has been used for centuries to treat liver disorders. The flavonolignan silibinin represents a natural antioxidant and the main bioactive ingredient of silymarin (silybin), a standard extract of its seeds. Mitochondrial dysfunction and the associated generation of reactive oxygen/nitrogen species (ROS/RNS) are involved in the development of chronic liver and age-related neurodegenerative diseases. Silibinin A (SIL A) is one of two diastereomers found in silymarin and was used to evaluate the effects of silymarin on mitochondrial parameters including mitochondrial membrane potential and ATP production with and without sodium nitroprusside- (SNP-) induced nitrosative stress, oxidative phosphorylation, and citrate synthase activity in HepG2 and PC12 cells. Both cell lines were influenced by SIL A, but at different concentrations. SIL A significantly weakened nitrosative stress in both cell lines. Low concentrations not only maintained protective properties but also increased basal mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) levels. However, these effects could not be associated with oxidative phosphorylation. On the other side, high concentrations of SIL A significantly decreased MMP and ATP levels. Although SIL A did not provide a general improvement of the mitochondrial function, our findings show that SIL A protects against SNP-induced nitrosative stress at the level of mitochondria making it potentially beneficial against neurological disorders.

Effect of hyperthermia and acidosis on equine skeletal muscle mitochondrial oxygen consumption

2020 ◽  
pp. 1-10
Author(s):  
M.S. Davis ◽  
M.R. Fulton ◽  
A. Popken
Keyword(s):  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Oxidative Phosphorylation ◽  
Muscle Fatigue ◽  
Mitochondrial Function ◽  
Mitochondrial Respiration ◽  
Complex I ◽  
Mitochondrial Oxygen Consumption ◽  
Biochemical Basis ◽  
Complex Ii

The skeletal muscle of exercising horses develops pronounced hyperthermia and acidosis during strenuous or prolonged exercise, with very high tissue temperature and low pH associated with muscle fatigue or damage. The purpose of this study was to evaluate the individual effects of physiologically relevant hyperthermia and acidosis on equine skeletal muscle mitochondrial function, using ex vivo measurement of oxygen consumption to assess the function of different mitochondrial elements. Fresh triceps muscle biopsies from 6 healthy unfit Thoroughbred geldings were permeabilised to permit diffusion of small molecular weight substrates through the sarcolemma and analysed in a high resolution respirometer at 38, 40, 42, and 44 °C, and pH=7.1, 6.5, and 6.1. Oxygen consumption was measured under conditions of non-phosphorylating (leak) respiration and phosphorylating respiration through Complex I and Complex II. Data were analysed using a one-way repeated measures ANOVA and data are expressed as mean ± standard deviation. Leak respiration was ~3-fold higher at 44 °C compared to 38 °C regardless of electron source (Complex I: 22.88±3.05 vs 8.08±1.92 pmol O2/mg/s), P=0.002; Complex II: 79.14±23.72 vs 21.43±11.08 pmol O2/mg/s, P=0.022), resulting in a decrease in efficiency of oxidative phosphorylation. Acidosis had minimal effect on mitochondrial respiration at pH=6.5, but pH=6.1 resulted in a 50% decrease in mitochondrial oxygen consumption. These results suggest that skeletal muscle hyperthermia decreases the efficiency of oxidative phosphorylation through increased leak respiration, thus providing a specific biochemical basis for hyperthermia-induced muscle fatigue. The effect of myocellular acidosis on mitochondrial respiration was minimal under typical levels of acidosis, but atypically severe acidosis can lead to impairment of mitochondrial function.

Sulphide oxidation and oxidative phosphorylation in the mitochondria of the lugworm

1997 ◽  
Vol 200 (1) ◽  
pp. 83-92 ◽  
Author(s):  
S Vökel ◽  
M K Grieshaber
Keyword(s):  
Oxygen Consumption ◽  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Cytochrome C Oxidase ◽  
Electron Flow ◽  
Respiratory Control ◽  
Sulphide Oxidation ◽  
Atp Production ◽  
Sulphide Concentration ◽  
Flow Through

Oxygen consumption, ATP production and cytochrome c oxidase activity of isolated mitochondria from body-wall tissue of Arenicola marina were measured as a function of sulphide concentration, and the effect of inhibitors of the respiratory complexes on these processes was determined. Concentrations of sulphide between 6 and 9 &micro;mol l-1 induced oxygen consumption with a respiratory control ratio of 1.7. Production of ATP was stimulated by the addition of sulphide, reaching a maximal value of 67 nmol min-1 mg-1 protein at a sulphide concentration of 8 &micro;mol l-1. Under these conditions, 1 mole of ATP was formed per mole of sulphide consumed. Higher concentrations of sulphide led to a decrease in ATP production until complete inhibition occurred at approximately 50 &micro;mol l-1. The production of ATP with malate and succinate was stimulated by approximately 15 % in the presence of 4 &micro;mol l-1 sulphide, but decreased at sulphide concentrations higher than 15&shy;20 &micro;mol l-1. Cytochrome c oxidase was also inhibited by sulphide, showing half-maximal inhibition at 1.5 &micro;mol l-1 sulphide. Sulphide-induced ATP production was inhibited by antimycin, cyanide and oligomycin but not by rotenone or salicylhydroxamic acid. The present data indicate that sulphide oxidation is coupled to oxidative phosphorylation solely by electron flow through cytochrome c oxidase, whereas the alternative oxidase does not serve as a coupling site. At sulphide concentrations higher than 20 &micro;mol l-1, oxidation of sulphide serves mainly as a detoxification process rather than as a source of energy.

scholarly journals The Relationship between Myoglobin, Aerobic Capacity, Nitric Oxide Synthase Activity and Mitochondrial Function in Fish Hearts

Antioxidants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1072
Author(s):  
Lucie Gerber ◽  
Kathy A. Clow ◽  
William R. Driedzic ◽  
Anthony K. Gamperl
Keyword(s):  
Nitric Oxide ◽  
Mitochondrial Function ◽  
Citrate Synthase ◽  
Coupling Efficiency ◽  
Hypoxia Tolerance ◽  
Compensatory Mechanisms ◽  
Dynamic Interactions ◽  
Myoxocephalus Scorpius ◽  
Species Production ◽  
Oxide Synthase

The dynamic interactions between nitric oxide (NO) and myoglobin (Mb) in the cardiovascular system have received considerable attention. The loss of Mb, the principal O2 carrier and a NO scavenger/producer, in the heart of some red-blooded fishes provides a unique opportunity for assessing this globin’s role in NO homeostasis and mitochondrial function. We measured Mb content, activities of enzymes of NO and aerobic metabolism [NO Synthase (NOS) and citrate synthase, respectively] and mitochondrial parameters [Complex-I and -I+II respiration, coupling efficiency, reactive oxygen species production/release rates and mitochondrial sensitivity to inhibition by NO (i.e., NO IC50)] in the heart of three species of red-blooded fish. The expression of Mb correlated positively with NOS activity and NO IC50, with low NOS activity and a reduced NO IC50 in the Mb-lacking lumpfish (Cyclopterus lumpus) as compared to the Mb-expressing Atlantic salmon (Salmo salar) and short-horned sculpin (Myoxocephalus scorpius). Collectively, our data show that NO levels are fine-tuned so that NO homeostasis and mitochondrial function are preserved; indicate that compensatory mechanisms are in place to tightly regulate [NO] and mitochondrial function in a species without Mb; and strongly suggest that the NO IC50 for oxidative phosphorylation is closely related to a fish’s hypoxia tolerance.

scholarly journals Methodological Issue of Mitochondrial Isolation in Acute-Injury Rat Model: Asphyxia Cardiac Arrest and Resuscitation

2021 ◽  
Vol 8 ◽  
Author(s):  
Tomoaki Aoki ◽  
Yu Okuma ◽  
Lance B. Becker ◽  
Kei Hayashida ◽  
Koichiro Shinozaki
Keyword(s):  
Cardiac Arrest ◽  
Cytochrome C ◽  
Mitochondrial Function ◽  
Sham Group ◽  
Citrate Synthase ◽  
Methodological Issue ◽  
Acute Injury ◽  
Adult Rats ◽  
Respiration Activity ◽  
Kidney Mitochondria

Background: Identification of the mechanisms underlying mitochondrial dysfunction is key to understanding the pathophysiology of acute injuries such as cardiac arrest (CA); however, effective methods for measurement of mitochondrial function associated with mitochondrial isolation have been debated for a long time. This study aimed to evaluate the dysregulation of mitochondrial respiratory function after CA while testing the sampling bias that might be induced by the mitochondrial isolation method.Materials and Methods: Adult rats were subjected to 10-min asphyxia-induced CA. 30 min after resuscitation, the brain and kidney mitochondria from animals in sham and CA groups were isolated (n = 8, each). The mitochondrial quantity, expressed as protein concentration (isolation yields), was determined, and the oxygen consumption rates were measured. ADP-dependent (state-3) and ADP-limited (state-4) respiration activities were compared between the groups. Mitochondrial quantity was evaluated based on citrate synthase (CS) activity and cytochrome c concentration, measured independent of the isolation yields.Results: The state-3 respiration activity and isolation yield in the CA group were significantly lower than those in the sham group (brain, p &lt; 0.01; kidney, p &lt; 0.001). The CS activity was significantly lower in the CA group as compared to that in the sham group (brain, p &lt; 0.01; kidney, p &lt; 0.01). Cytochrome c levels in the CA group showed a similar trend (brain, p = 0.08; kidney, p = 0.25).Conclusions: CA decreased mitochondrial respiration activity and the quantity of mitochondria isolated from the tissues. Owing to the nature of fragmented or damaged mitochondrial membranes caused by acute injury, there is a potential loss of disrupted mitochondria. Thus, it is plausible that the mitochondrial function in the acute-injury model may be underestimated as this loss is not considered.

A new insight into the molecular hydrogen effect on coenzyme Q and mitochondrial function of rats

2020 ◽  
Vol 98 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Anna Gvozdjáková ◽  
Jarmila Kucharská ◽  
Branislav Kura ◽  
Ol’ga Vančová ◽  
Zuzana Rausová ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Oxidative Phosphorylation ◽  
Respiratory Chain ◽  
Mitochondrial Function ◽  
Complex I ◽  
Molecular Hydrogen ◽  
Coenzyme Q ◽  
Complex Ii ◽  
Atp Production ◽  
Q Cycle

Mitochondria are the major source of cellular energy metabolism. In the cardiac cells, mitochondria produce by way of the oxidative phosphorylation more than 90% of the energy supply in the form of ATP, which is utilized in many ATP-dependent processes, like cycling of the contractile proteins or maintaining ion gradients. Reactive oxygen species (ROS) are by-products of cellular metabolism and their levels are controlled by intracellular antioxidant systems. Imbalance between ROS and the antioxidant defense leads to oxidative stress and oxidative changes to cellular biomolecules. Molecular hydrogen (H2) has been proved as beneficial in the prevention and therapy of various diseases including cardiovascular disorders. It selectively scavenges hydroxyl radical and peroxynitrite, reduces oxidative stress, and has anti-inflammatory and anti-apoptotic effects. The effect of H2 on the myocardial mitochondrial function and coenzyme Q levels is not well known. In this paper, we demonstrated that consumption of H2-rich water (HRW) resulted in stimulated rat cardiac mitochondrial electron respiratory chain function and increased levels of ATP production by Complex I and Complex II substrates. Similarly, coenzyme Q9 levels in the rat plasma, myocardial tissue, and mitochondria were increased and malondialdehyde level in plasma was reduced after HRW administration. Based on obtained data, we hypothesize a new metabolic pathway of the H2 effect in mitochondria on the Q-cycle and in mitochondrial respiratory chain function. The Q-cycle contains three coenzyme Q forms: coenzyme Q in oxidized form (ubiquinone), radical form (semiquinone), or reduced form (ubiquinol). H2 may be a donor of both electron and proton in the Q-cycle and thus we can suppose stimulation of coenzyme Q production. When ubiquinone is reduced to ubiquinol, lipid peroxidation is reduced. Increased CoQ9 concentration can stimulate electron transport from Complex I and Complex II to Complex III and increase ATP production via mitochondrial oxidative phosphorylation. Our results indicate that H2 may function to prevent/treat disease states with disrupted myocardial mitochondrial function.

scholarly journals Powerhouses in the cold: mitochondrial function during thermal acclimation in montane mayflies

2019 ◽  
Vol 375 (1790) ◽  
pp. 20190181 ◽  
Author(s):  
Justin C. Havird ◽  
Alisha A. Shah ◽  
Adam J. Chicco
Keyword(s):  
Mitochondrial Function ◽  
Citrate Synthase ◽  
Coupling Efficiency ◽  
High Elevation ◽  
Thermal Acclimation ◽  
Environmental Adaptation ◽  
Genetic Changes ◽  
Mitochondrial Genotype ◽  
Complex Relationships ◽  
Titration Protocol

Mitochondria provide the vast majority of cellular energy available to eukaryotes. Therefore, adjustments in mitochondrial function through genetic changes in mitochondrial or nuclear-encoded genes might underlie environmental adaptation. Environmentally induced plasticity in mitochondrial function is also common, especially in response to thermal acclimation in aquatic systems. Here, we examined mitochondrial function in mayfly larvae ( Baetis and Drunella spp.) from high and low elevation mountain streams during thermal acclimation to ecologically relevant temperatures. A multi-substrate titration protocol was used to evaluate different respiratory states in isolated mitochondria, along with cytochrome oxidase and citrate synthase activities. In general, maximal mitochondrial respiratory capacity and oxidative phosphorylation coupling efficiency decreased during acclimation to higher temperatures, suggesting montane insects may be especially vulnerable to rapid climate change. Consistent with predictions of the climate variability hypothesis, mitochondria from Baetis collected at a low elevation site with highly variable daily and seasonal temperatures exhibited greater thermal tolerance than Baetis from a high elevation site with comparatively stable temperatures. However, mitochondrial phenotypes were more resilient than whole-organism phenotypes in the face of thermal stress. These results highlight the complex relationships between mitochondrial and organismal genotypes, phenotypes and environmental adaptation. This article is part of the theme issue ‘Linking the mitochondrial genotype to phenotype: a complex endeavour’.

scholarly journals The influence of osmolarity on the reduction of exogenous cytochrome c and permeability of the inner membrane of Jerusalem artichoke mitochondria

1974 ◽  
Vol 140 (1) ◽  
pp. 79-86 ◽  
Author(s):  
John M. Palmer ◽  
Betty I. Kirk
Keyword(s):  
Cytochrome C ◽  
Outer Membrane ◽  
Electron Flow ◽  
Jerusalem Artichoke ◽  
Simultaneous Increase ◽  
Permeability Barrier ◽  
Activation Process ◽  
Inner Membrane ◽  
Cytochrome C Reductase ◽  
Succinate Cytochrome C Reductase

The stimulation of succinate–cytochrome c reductase in Jerusalem artichoke mitochondria by lowering osmolarity was found to be associated with conformational changes in the inner membrane rather than with rupture of the outer membrane. This conclusion is based on the following evidence. (1) When the activation of succinate dehydrogenase was measured by using either K3Fe(CN)6 or exogenous cytochrome c as an electron acceptor, electron flow to cytochrome c was always 7% of that to K3Fe(CN)6 throughout the activation process. (2) The rate of exogenous cytochrome c reduction by succinate and NADH was directly related to the maximum rate of electron flow as determined by oxygen utilization. These two observations are not consistent with the low rate of succinate–cytochrome c reductase being limited by a permeability barrier at the outer membrane. (3) In addition to stimulating the succinate–cytochrome c reductase, lowering the osmolarity caused simultaneous changes in the permeability of the inner membrane to ferricyanide and NADH. The data show that lowering the osmolarity results in progressive changes in the permeability of the inner membrane. The first change detected was an increased permeability to K3Fe(CN)6, then a simultaneous increase in accessibility of the respiratory chain to exogenous cytochrome c and an increased permeability to NADH, followed finally by rupture as measured by the release of malate dehydrogenase.

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