scholarly journals Diabetes-associated dysregulation ofO-GlcNAcylation in rat cardiac mitochondria

2015 ◽  
Vol 112 (19) ◽  
pp. 6050-6055 ◽  
Author(s):  
Partha S. Banerjee ◽  
Junfeng Ma ◽  
Gerald W. Hart
Keyword(s):  
Mitochondrial Dysfunction ◽  
Rat Heart ◽  
Mitochondrial Membrane ◽  
Diabetic Rats ◽  
Neonatal Rat ◽  
Heart Mitochondria ◽  
Cardiac Mitochondria ◽  
Rat Cardiomyocytes ◽  
Pyrimidine Nucleotide ◽  
Rat Heart Mitochondria

Elevated mitochondrialO-GlcNAcylation caused by hyperglycemia, as occurs in diabetes, significantly contributes to mitochondrial dysfunction and to diabetic cardiomyopathy. However, little is known about the enzymology of mitochondrialO-GlcNAcylation. Herein, we investigated the enzymes responsible for cyclingO-GlcNAc on mitochondrial proteins and studied the mitochondrial transport of UDP-GlcNAc. Analyses of purified rat heart mitochondria from normal and streptozocin-treated diabetic rats show increased mitochondrialO-GlcNAc transferase (OGT) and a concomitant decrease in the mito-specific O-GlcNAcase (OGA). Strikingly, OGT is mislocalized in cardiac mitochondria from diabetic rats. Interaction of OGT and complex IV observed in normal rat heart mitochondria is visibly reduced in diabetic samples, where OGT is mislocalized to the matrix. Live cell OGA activity assays establish the presence of O-GlcNAcase within the mitochondria. Furthermore, we establish that the inner mitochondrial membrane transporter, pyrimidine nucleotide carrier, transports UDP-GlcNAc from the cytosol to the inside of the mitochondria. Knockdown of this transporter substantially lowers mitochondrialO-GlcNAcylation. Inhibition of OGT or OGA activity within neonatal rat cardiomyocytes significantly affects energy production, mitochondrial membrane potential, and mitochondrial oxygen consumption. These data suggest that cardiac mitochondria not only have robustO-GlcNAc cycling, but also that dysregulation ofO-GlcNAcylation likely plays a key role in mitochondrial dysfunction associated with diabetes.

Abstract 104: Effects of Pinacidil and Ca 2 + on Sodium-loaded Rat Heart Mitochondria

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Sergey M Korotkov ◽  
Vladimir P Nesterov ◽  
Irina V Brailovskaya ◽  
Larisa V Emelyanova ◽  
Svetlana A Konovalova ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Rat Heart ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition ◽  
Ischemia Reperfusion ◽  
Potassium Acetate ◽  
Heart Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Rat Heart Mitochondria ◽  
Acetate Medium

Deterioration of the contractile parameters of the heart muscle caused by ischemia and followed reperfusion is known as the main postoperative complication which is related to Ca 2+ and Na + overload in cardiomyocytes and mitochondria. Pinacidil reduced the overload in ischemia/reperfusion experiments. The mechanism of this phenomenon is still not clear. We hypothesized that increased ion permeability of the inner mitochondrial membrane (IMM) followed drop of electrochemical potential (ΔΨ mito ) can reduce the calcium. The aim of the study was to elucidate the effect of pinacidil (100 μM) and Ca 2+ (100 μM ) on swelling, oxygen consumption and ΔΨ mito of isolated sodium-loaded rat heart mitochondria (RHM(Na)) energized glutamate and malate. Pinacidil significantly enchanced the permeability of IMM to protons in ammonium nitrate medium. Also increased swelling of RHM(Na) energized with substrates in potassium acetate medium revealed that pinacidil increased potassium transport into matrix. Pinacidil stimulated oxygen consumption of RHM(Na) in State 4 and detained Ca 2+ -induced dissipation of ΔΨ mito . Under condition of Ca 2+ and Na + overload simulating ischemia/reperfusion, RHM(Na) oxygen consumption was not affected with pinacidil in State 3 and in the presence of 2,4-dinitrophenol. Cyclosporin A and ADP, the inhibitors of mitochondrial permeability transition pore (MPTP), markedly decreased Ca 2+ - induced swelling of RHM(Na) in nitrate ammonium or potassium acetate medium in the presence of pinacidil. Carboxyatractyloside, an inhibitor of cytosolic side-specific adenine nucleotide translocase, eliminated a pinacidil-stimulated oxygen consumption of succinate-energized RHMNa in State 4 regardless of the presence of Ca 2+ . Pinacidil was also concluded to accelerat potassium flux into energized RHM(Na) and promot MPTP opening in the low conduction state. Based on our data we suggested that the effect of pharmacological preconditioning induced by pinacidil could be due to it’s direct effect on mitochondria which is connected with above stimulation of the potassium permeability of the inner mitochondrial membrane and following reduce of the ΔΨ mito that thus prevent calcium overload of cardiomyocytes after ischemia/reperfusion in turn.

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 Incorporation of [32P]phosphate into the pyruvate dehydrogenase complex in rat heart mitochondria

1980 ◽  
Vol 188 (2) ◽  
pp. 409-421 ◽  
Author(s):  
G J Sale ◽  
P J Randle
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Rat Heart ◽  
Pyruvate Dehydrogenase Complex ◽  
Diabetic Rats ◽  
Heart Mitochondria ◽  
Kinase Reaction ◽  
Rat Heart Mitochondria ◽  
Dehydrogenase Complex

1. Evidence is given for three sites of phosphorylation in the alpha-chains of the decarboxylase component of purified rat heart pyruvate dehydrogenase complex, analogous to those established for procine and bovine complexes. Inactivation of rat heart complex was correlated with phosphorylation of site 1. Relative initial rates of phosphorylation were site 1 greater than site 2 greater than site 3. 2. Methods are described for measurement of incorporation of 32Pi into the complex in rat heart mitochondria oxidizing 2-oxoglutarate + L-malate (total, sites 1, 2 and 3). Inactivation of the complex was related linearly to phosphorylation of site 1 in mitochondria of normal or diabetic rats. The relative initial rates of phosphorylation were site 1 greater than site 2 greater than site 3. Rates of site-2 and site-3 phosphorylation may have been closer to that of site 1 in mitochondria of diabetic rats than in mitochondria of normal rats. 3. The concentration of inactive (phosphorylated) complex was varied in mitochondria from normal rats by inhibiting the kinase reaction with pyruvate at concentrations ranging from 0.15 to 0.4 mM. The results showed that the concentration of inactive complex is related linearly to incorporation of 32Pi into site 1. Inhibition of 32Pi incorporations with pyruvate at all concentrations over this range was site 3 greater than site 2 greater than site 1. 4. With mitochondria from diabetic rats, pyruvate (0.15-0.4 mM) inhibited incorporation of 32Pi into site 3, but it had no effect on the concentration of inactive complex or on incorporations of 32Pi into site 1 or site 2. It is concluded that site-3 phosphorylation is not required for inactivation of the complex in rat heart mitochondria. 5. Evidence is given that phosphorylation of sites 2 and 3 may inhibit reactivation of the complex by dephosphorylation in rat heart mitochondria.

scholarly journals Astaxanthin Prevents Mitochondrial Impairment Induced by Isoproterenol in Isolated Rat Heart Mitochondria

Antioxidants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 262 ◽  
Author(s):  
Olga Krestinina ◽  
Yulia Baburina ◽  
Roman Krestinin ◽  
Irina Odinokova ◽  
Irina Fadeeva ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Rat Heart ◽  
Adenine Nucleotide ◽  
Heart Function ◽  
Isolated Rat Heart ◽  
Heart Mitochondria ◽  
Cyclophilin D ◽  
Inner Mitochondrial Membrane ◽  
Respiratory Chain Complexes ◽  
Rat Heart Mitochondria

Mitochondria are considered to be a power station of the cell. It is known that they play a major role in both normal and pathological heart function. Alterations in mitochondrial bioenergetics are one of the main causes of the origin and progression of heart failure since they have an inhibitory effect on the activity of respiratory complexes in the inner mitochondrial membrane. Astaxanthin (AST) is a xanthophyll carotenoid of mainly marine origin. It has both lipophilic and hydrophilic properties and may prevent mitochondrial dysfunction by permeating the cell membrane and co-localizing within mitochondria. The carotenoid suppresses oxidative stress-induced mitochondrial dysfunction and the development of diseases. In the present study, it was found that the preliminary oral administration of AST upregulated the activity of respiratory chain complexes and ATP synthase and the level of their main subunits, thereby improving the respiration of rat heart mitochondria (RHM) in the heart injured by isoproterenol (ISO). AST decreased the level of cyclophilin D (CyP-D) and increased the level of adenine nucleotide translocase (ANT) in this condition. It was concluded that AST could be considered as a potential mitochondrial-targeted agent in the therapy of pathological conditions associated with oxidative damage and mitochondrial dysfunction. AST, as a dietary supplement, has a potential in the prevention of cardiovascular diseases.

scholarly journals Uptake of safranine by cardiac mitochondria. Competition with calcium ions and dependence on anions

1980 ◽  
Vol 192 (2) ◽  
pp. 551-557 ◽  
Author(s):  
E J Harris ◽  
H Baum
Keyword(s):  
Calcium Ions ◽  
Rat Heart ◽  
Heart Mitochondria ◽  
Cardiac Mitochondria ◽  
Residual Concentration ◽  
Uptake Process ◽  
Rat Heart Mitochondria ◽  
Hydrolysis Of

Some characteristics of the energized uptake of safranine by rat heart mitochondria were studied. When monitored by changes in differential absorbance (between 524 and 554 nm) of a whole suspension in safranine-containing medium, the changes seen are not linearly related to the quantity of the safranine moving. It happens coincidentally that the changes observed are nearly linearly related to the logarithm of the ratio between the accumulated safranine and its residual concentration in the medium; this explains why the changes of absorbance have been found by other authors to be linearly related to the logarithms of the ratio of internal/external concentrations of such other cations as are permeable. The uptake process appears to compete for energy with Ca2+ uptake and vice versa. Energized safranine uptake has an anion requirement, which is seen when movement of endogenous Pi has been inhibited; the small residual safranine uptake obtained when energy is provided in the presence of mersalyl may be attributable to internal Pi. However, a limited anion-independent energized uptake of safranine, in exchange for internal K+, may be elicited in the presence of nigericin. Adding ATP to the energized system in the presence of an inhibitor of Pi movement elicits an additional uptake of safranine that is oligomycin-sensitive and that probably arises on account of generation of internal Pi by hydrolysis of the entering ATP.

Effects of hydrogen peroxide and hypochlorite on membrane potential of mitochondria in situ in rat heart cells

1991 ◽  
Vol 69 (11) ◽  
pp. 1705-1712 ◽  
Author(s):  
Noburu Konno ◽  
K. J. Kako
Keyword(s):  
Hydrogen Peroxide ◽  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Rat Heart ◽  
Mitochondrial Membrane ◽  
Isolated Rat Heart ◽  
Heart Mitochondria ◽  
High Concentrations ◽  
Isolated Rat

Hydrogen peroxide (H2O2) and hypochlorite (HOCl) cause a variety of cellular dysfunctions. In this study we examined the effects of these agents on the electrical potential gradient across the inner membrane of mitochondria in situ in isolated rat heart myocytes. Myocytes were prepared by collagenase digestion and incubated in the presence of H2O2 or HOCl. Transmembrane electrical gradients were measured by distribution of [3H]triphenylmethylphosphonium+, a lipophilic cation. The particulate fraction was separated from the cytosolic compartment first by permeabilization using digitonin, followed by rapid centrifugal sedimentation through a bromododecane layer. We found that the mitochondrial membrane potential (161 ± 7 mV, negative inside) was relatively well maintained under oxidant stress, i.e., the potential was decreased only at high concentrations of HOCl and H2O2 and gradually with time. The membrane potential of isolated rat heart mitochondria was affected similarly by H2O2 and HOCl in a concentration- and time-dependent manner. High concentrations of oxidants also reduced the cellular ATP level but did not significantly change the matrix volume. When the extra-mitochondrial free calcium concentration was increased in permeabilized myocytes, the transmembrane potential was decreased proportionally, and this decrease was potentiated further by H2O2. These results support the view that heart mitochondria are equipped with well-developed defense mechanisms against oxidants, but the action of H2O2 on the transmembrane electrical gradient is exacerbated by an increase in cytosolic calcium. Keywords: ATP, calcium, cardiomyocyte, cell defense, mitochondrial membrane potential, oxidant, triphenylmethylphosphonium.

scholarly journals Conversion of inactive (phosphorylated) pyruvate dehydrogenase complex into active complex by the phosphate reaction in heart mitochondria is inhibited by alloxan-diabetes or starvation in the rat

1978 ◽  
Vol 173 (2) ◽  
pp. 669-680 ◽  
Author(s):  
N J Hutson ◽  
A L Kerbey ◽  
P J Randle ◽  
P H Sugden
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Rat Heart ◽  
Pyruvate Dehydrogenase Complex ◽  
Diabetic Rats ◽  
Atp Depletion ◽  
Heart Mitochondria ◽  
Active Complex ◽  
Phosphate Complex ◽  
Rat Hearts ◽  
Dehydrogenase Complex

1. The conversion of inactive (phosphorylated) pyruvate dehydrogenase complex into active (dephosphorylated) complex by pyruvate dehydrogenase phosphate phosphatase is inhibited in heart mitochondria prepared from alloxan-diabetic or 48h-starved rats, in mitochondria prepared from acetate-perfused rat hearts and in mitochondria prepared from normal rat hearts incubated with respiratory substrates for 6 min (as compared with 1 min). 2. This conclusion is based on experiments with isolated intact mitochondria in which the pyruvate dehydrogenase kinase reaction was inhibited by pyruvate or ATP depletion (by using oligomycin and carbonyl cyanide m-chlorophenylhydrazone), and in experiments in which the rate of conversion of inactive complex into active complex by the phosphatase was measured in extracts of mitochondria. The inhibition of the phosphatase reaction was seen with constant concentrations of Ca2+ and Mg2+ (activators of the phosphatase). The phosphatase reaction in these mitochondrial extracts was not inhibited when an excess of exogenous pig heart pyruvate dehydrogenase phosphate was used as substrate. It is concluded that this inhibition is due to some factor(s) associated with the substrate (pyruvate dehydrogenase phosphate complex) and not to inhibition of the phosphatase as such. 3. This conclusion was verified by isolating pyruvate dehydrogenase phosphate complex, free of phosphatase, from hearts of control and diabetic rats an from heart mitochondria incubed for 1min (control) or 6min with respiratory substrates. The rates of re-activation of the inactive complexes were then measured with preparations of ox heart or rat heart phosphatase. The rates were lower (relative to controls) with inactive complex from hearts of diabetic rats or from heart mitochondria incubated for 6min with respiratory substrates. 4. The incorporation of 32Pi into inactive complex took 6min to complete in rat heart mitocondria. The extent of incorporation was consistent with three or four sites of phosphorylation in rat heart pyruvate dehydrogenase complex. 5. It is suggested that phosphorylation of sites additional to an inactivating site may inhibit the conversion of inactive complex into active complex by the phosphatase in heart mitochondria from alloxan-diabetic or 48h-starved rats or in mitochondria incubated for 6min with respiratory substrates.

Magnolol and honokiol isolated from magnolia officinalis protect rat heart mitochondria against lipid peroxidation

1994 ◽  
Vol 47 (3) ◽  
pp. 549-553 ◽  
Author(s):  
Yu-Chiang Lo ◽  
Teng Che-Ming ◽  
Chen Chieh-Fu ◽  
Chen Chien-Chih ◽  
Hong Chuang-Ye
Keyword(s):  
Lipid Peroxidation ◽  
Rat Heart ◽  
Heart Mitochondria ◽  
Rat Heart Mitochondria ◽  
Magnolia Officinalis
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