scholarly journals Actions of the creatine analogue β-guanidinopropionic acid on rat heart mitochondria

1994 ◽  
Vol 300 (1) ◽  
pp. 211-216 ◽  
Author(s):  
J F Clark ◽  
Z Khuchua ◽  
A V Kuznetsov ◽  
E Vassil'eva ◽  
E Boehm ◽  
...  
Keyword(s):  
Creatine Kinase ◽  
Rat Heart ◽  
Heart Mitochondria ◽  
Isolated Cardiomyocytes ◽  
Isolated Mitochondria ◽  
Significant Stimulation ◽  
Ionic Detergent ◽  
Rat Heart Mitochondria ◽  
Kinetics Of ◽  
Stimulation Of

The action of the creatine analogue beta-guanidinopropionic acid (beta-GPA) was examined in rat heart mitochondria and in isolated cardiomyocytes or fibres which were permeabilized with the non-ionic detergent saponin to determine the kinetics of mitochondrial creatine kinase for beta-GPA. Fibres and myocytes were subjected to increasing [ADP] in the presence and absence of beta-GPA or creatine, whereas isolated mitochondria received a similar protocol with increasing [ATP]. In isolated mitochondria given ATP, there was a stimulation of respiration by creatine, but no significant stimulation of respiration by beta-GPA. Further studies on fibres from control and beta-GPA-fed rats also found that beta-GPA is not utilized by the mitochondria, as evidenced by a lack of beta-GPA-stimulated respiration (Km for ADP = 142 +/- 23 microM) compared with control (Km for ADP from 161 +/- 23 microM), but no significant change in Vmax. Therefore the rat heart mitochondria are not responsive to beta-GPA as compared with creatine. Interestingly, the fibres from beta-GPA-fed rats had no creatine- or beta-GPA-stimulated respiration (Km for ADP = 57.3 +/- 7.2 microM for control, 54.2 +/- 7.2 microM with creatine, and 53.5 +/- 7.8 microM with beta-GPA). The mitochondria prepared from the hearts of rats exposed for 10 weeks to 1% beta-GPA in their diet had a significant decrease in Vmax. and a significant decrease in Km for ADP. Thus the hearts from beta-GPA-fed animals may be pathologic, due to a disruption of the creatine kinase energy circuit.

scholarly journals Celecoxib Decreases Mitochondrial Complex IV Activity and Induces Oxidative Stress in Isolated Rat Heart Mitochondria: An Analysis for its Cardiotoxic Adverse Effect

2020 ◽  
Author(s):  
Saman Atashbar ◽  
Elham Mohammad Khanlou ◽  
Saleh Khezri ◽  
Peyman Kurdpour ◽  
Ahmad Salimi
Keyword(s):  
Lipid Peroxidation ◽  
Rat Heart ◽  
Isolated Rat Heart ◽  
Mitochondrial Swelling ◽  
Heart Mitochondria ◽  
Isolated Mitochondria ◽  
Biochemical Assays ◽  
Ros Formation ◽  
Rat Heart Mitochondria ◽  
Isolated Rat

Abstract Background In spite of the cardiotoxic effect of selective cyclooxygenase-2 inhibitors, they are most widely used as anti-inflammatory and analgesic drugs. Today, valdecoxib and rofecoxib have been withdrawn on the market but celecoxib remains. In this study, we focused on an analysis of celecoxib toxic effects on isolated mitochondrial. Methods isolated rat heart mitochondria were obtained using differential centrifugation. Using flowcytometry and biochemical assays we searched succinate dehydrogenases (SDH), mitochondrial membrane potential (MMP), reactive oxygen species (ROS) formation, mitochondrial swelling, lipid peroxidation and mitochondrial complexes activity in rat heart isolated mitochondria. Results In here our results indicated a significant decrease in activity of complexes IV after exposure with celecoxib (16 µg/ml). This decrease in activity of complexes IV is paralleled by the MMP collapse, ROS formation, mitochondrial swelling and lipid peroxidation. Conclusion For the first time, this introductory study has showed a significant decrease in activity of complexes IV and mitochondrial dysfunction after exposure with celecoxib in rat heart isolated mitochondria.

scholarly journals Ca2+ stimulates both the respiratory and phosphorylation subsystems in rat heart mitochondria

1996 ◽  
Vol 320 (1) ◽  
pp. 329-334 ◽  
Author(s):  
Vida MILDAZIENE ◽  
Rasa BANIENE ◽  
Zita NAUCIENE ◽  
Ausra MARCINKEVICIUTE ◽  
Ramune MORKUNIENE ◽  
...  
Keyword(s):  
Rat Heart ◽  
Mitochondrial Membrane ◽  
Isolated Rat Heart ◽  
Heart Mitochondria ◽  
Proton Leak ◽  
Succinate Oxidation ◽  
Kinetic Dependence ◽  
Intermediate States ◽  
Rat Heart Mitochondria ◽  
Stimulation Of

Stimulation of mitochondrial respiration by physiological concentrations of Ca2+ was studied to determine which components of oxidative phosphorylation are affected by Ca2+. The kinetic dependence of the respiratory chain, phosphorylation subsystem and proton leak on the mitochondrial membrane potential in isolated rat heart mitochondria respiring on 2-oxoglutarate or succinate was measured at two different concentrations of external free Ca2+. The results show that proton leak is not directly affected by Ca2+, but that both the respiratory and phosphorylation systems can be directly stimulated by Ca2+ depending on conditions. Although Ca2+ directly stimulates the phosphorylation system, this has relatively little effect on respiration rate with 2-oxoglutarate in States 3 and 4 because the subsystem has little control over respiration. However, in intermediate states, the phosphorylation system has greater control and Ca2+ stimulation of this system contributes substantially to the stimulation of respiration and phosphorylation. In the case of succinate oxidation neither the respiratory subsystem nor the phosphorylation system is stimulated by Ca2+.

scholarly journals The mitochondrial pyruvate carrier. Kinetics and specificity for substrates and inhibitors

1975 ◽  
Vol 148 (1) ◽  
pp. 85-96 ◽  
Author(s):  
A P Halestrap
Keyword(s):  
Rat Heart ◽  
Competitive Inhibitor ◽  
Structural Features ◽  
Heart Mitochondria ◽  
Aromatic Side Chain ◽  
Mitochondrial Pyruvate Carrier ◽  
Transport Inhibitors ◽  
Rat Heart Mitochondria ◽  
Rate Limiting ◽  
Kinetics Of

1. Studies on the kinetics of pyruvate transport into mitochondria by an ‘inhibitor-stop’ technique were hampered by the decarboxylation of pyruvate by mitochondria even in the presence of rotenone. Decarboxylation was minimal at 6 degrees C. At this temperature the Km for pyruvate was 0.15 mM and Vmax. was 0.54nmol/min per mg of protein; α-cyano-4-hydroxycinnamate was found to be a non-competitive inhibitor, Ki 6.3 muM, and phenyl-pyruvate a competitive inhibitor, Ki 1.8 mM. 2. At 100 muM concentration, α-cyano-4-hydroxycinnamate rapidly and almost totally inhibited O2 uptake by rat heart mitochondria oxidizing pyruvate. Inhibition could be detected at concentrations of inhibitor as low as 1 muM although inhibition took time to develop at this concentration. Inhibition could be reversed by diluting out the inhibitor. 3. Various analogues of α-cyano-4-hydroxycinnamate were tested on rat liver and heart mitochondria. The important structural features appeared to be the α-cyanopropenoate group and the hydrophobic aromatic side chain. α-Cyanocinnamate, α-cyano-5-phenyl-2,4-pentadienoate and compound UK 5099 [α-cyano-β-(2-phenylindol-3-yl)acrylate] were all more powerful inhibitors than α-cyano-4-hydroxycinnamate showing 50% inhibition of pyruvate-dependent O2 consumption by rat heart mitochondria at concentrations of 200, 200 and 50 nM respectively. 4. The specificity of the carrier for its substrate was studied by both influx and efflux experiments. Oxamate, 2-oxobutyrate, phenylpyruvate, 2-oxo-4-methyl-pentanoate, chloroacetate, dichloroacetate, difluoroacetate, 2-chloropropionate, 3-chloropropionate and 2,2-dichloropropionate all exchanged with pyruvate, whereas acetate, lactate and trichloroacetate did not. 5. Pyruvate entry into the mitochondria was shown to be accompanied by the transport of a proton (or by exchange with an OH-ion). This proton flux was inhibited by α-cyano-4-hydroxycinnamate and allowed measurements of pyruvate transport at higher temperatures to be made. The activation energy of mitochondrial pyruvate transport was found to be 113 kJ (27 kcal)/mol and by extrapolation the rate of transport of pyruvate at 37 degrees C to be 42 nmol/min per mg of protein. The possibility that pyruvate transport into mitochondria may be rate limiting and involved in the regulation of gluconegenesis is discussed. 6. The transport of various monocarboxylic acids into mitochondria was studied by monitoring proton influx. The transport of dichloroacetate, difluoroacetate and oxamate appeared to be largely dependent on the pyruvate carrier and could be inhibited by pyruvate-transport inhibitors. However, many other halogenated and 2-oxo acids which could exchange with pyruvate on the carrier entered freely even in the presence of inhibitor.

Calcitriol Reduces Adverse Effects of Diclofenac on Mitochondrial Function in Isolated Rat Heart Mitochondria

Drug Research ◽  
2020 ◽  
Vol 70 (07) ◽  
pp. 317-324
Author(s):  
Saleh Khezri ◽  
Saman Atashbar ◽  
Sepideh Azizian ◽  
Zahra Shaikhgermchi ◽  
Peyman Kurdpour ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Function ◽  
Rat Heart ◽  
Cardiovascular Effects ◽  
Isolated Rat Heart ◽  
Heart Mitochondria ◽  
Mitochondrial Toxicity ◽  
Isolated Mitochondria ◽  
Rat Heart Mitochondria ◽  
And Oxidative Stress

AbstractThe safety of diclofenac (DIC) use in clinical practice has been questioned because of adverse cardiovascular effects. Previous studies have indicated that DIC cause mitochondrial dysfunction and oxidative stress in heart mitochondria. The aim of this study was to investigate the protective effect of calcitriol against the mitochondrial toxicity potency of diclofenac in heart rat mitochondria. For this purpose, rat heart mitochondria were isolated with mechanical lysis and differential centrifugation. Then isolated mitochondria were pretreated with 3 different concentrations of calcitriol (2.5, 5 and 10 µM) for 5 min at 37°C, after which DIC (10 µg/ml) was added to promote deleterious effects on mitochondria. During 1 hour of incubation, using by flow cytometry and biochemical evaluations, the parameters of mitochondrial toxicity were evaluated. Our results showed that DIC (10 µg/ml) caused a significant decrease in succinate dehydrogenase (SDH) activity, mitochondrial membrane potential (MMP) collapse, and mitochondrial swelling, and a significant increase in reactive oxygen species (ROS) formation, lipid peroxidation (LP) and oxidative stress. Also, our results revealed that co-administration of calcitriol (5 and 10 µM) with diclofenac markedly ameliorates the mitochondrial toxicity effects in rat hart mitochondria. In this study, we showed that DIC impairs mitochondrial function and induces mitochondrial toxicity in rat heart isolated mitochondria, which were ameliorated by calcitriol. These findings suggest that calcitriol may be a preventive/therapeutic strategy for cardiotoxicity complications caused by DIC.

scholarly journals Creatine Kinase of Rat Heart Mitochondria

1973 ◽  
Vol 248 (13) ◽  
pp. 4803-4810 ◽  
Author(s):  
William E. Jacobus ◽  
Albert L. Lehninger
Keyword(s):  
Creatine Kinase ◽  
Rat Heart ◽  
Heart Mitochondria ◽  
Rat Heart Mitochondria
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