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Jespersen NR, Yokota T, Støttrup NB, Bergdahl A, Paelestik KB, Povlsen JA, Dela F, Bøtker HE. Pre-ischaemic mitochondrial substrate constraint by inhibition of malate-aspartate shuttle preserves mitochondrial function after ischaemia-reperfusion. J Physiol 2017; 595:3765-3780. [PMID: 28093764 DOI: 10.1113/jp273408] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 01/12/2017] [Indexed: 01/26/2023] Open
Abstract
KEY POINTS Pre-ischaemic administration of aminooxiacetate (AOA), an inhibitor of the malate-aspartate shuttle (MAS), provides cardioprotection against ischaemia-reperfusion injury. The underlying mechanism remains unknown. We examined whether transient inhibition of the MAS during ischaemia and early reperfusion by AOA treatment could prevent mitochondrial damage at later reperfusion. The AOA treatment preserved mitochondrial respiratory capacity with reduced mitochondrial oxidative stress during late reperfusion to the same extent as ischaemic preconditioning (IPC). However, AOA treatment, but not IPC, reduced the myocardial interstitial concentration of tricarboxylic acid cycle intermediates at the onset of reperfusion. The results obtained in the present study demonstrate that metabolic regulation by inhibition of the MAS at the onset of reperfusion may be beneficial for the preservation of mitochondrial function during late reperfusion in an IR-injured heart. ABSTRACT Mitochondrial dysfunction plays a central role in ischaemia-reperfusion (IR) injury. Pre-ischaemic administration of aminooxyacetate (AOA), an inhibitor of the malate-aspartate shuttle (MAS), provides cardioprotection against IR injury, although the underlying mechanism remains unknown. We hypothesized that a transient inhibition of the MAS during ischaemia and early reperfusion could preserve mitochondrial function at later phase of reperfusion in the IR-injured heart to the same extent as ischaemic preconditioning (IPC), which is a well-validated cardioprotective strategy against IR injury. In the present study, we show that pre-ischaemic administration of AOA preserved mitochondrial complex I-linked state 3 respiration and fatty acid oxidation during late reperfusion in IR-injured isolated rat hearts. AOA treatment also attenuated the excessive emission of mitochondrial reactive oxygen species during state 3 with complex I-linked substrates during late reperfusion, which was consistent with reduced oxidative damage in the IR-injured heart. As a result, AOA treatment reduced infarct size after reperfusion. These protective effects of MAS inhibition on the mitochondria were similar to those of IPC. Intriguingly, the protection of mitochondrial function by AOA treatment appears to be different from that of IPC because AOA treatment, but not IPC, downregulated myocardial tricarboxilic acid (TCA)-cycle intermediates at the onset of reperfusion. MAS inhibition thus preserved mitochondrial respiratory capacity and decreased mitochondrial oxidative stress during late reperfusion in the IR-injured heart, at least in part, via metabolic regulation of TCA cycle intermediates in the mitochondria at the onset of reperfusion.
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Affiliation(s)
| | - Takashi Yokota
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Andreas Bergdahl
- Department of Exercise Science, Concordia University, Montreal, Canada
| | | | | | - Flemming Dela
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Geriatrics, Bispebjerg University Hospital, Copenhagen, Denmark
| | - Hans Erik Bøtker
- Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
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Lesnefsky EJ, Chen Q, Tandler B, Hoppel CL. Mitochondrial Dysfunction and Myocardial Ischemia-Reperfusion: Implications for Novel Therapies. Annu Rev Pharmacol Toxicol 2017; 57:535-565. [PMID: 27860548 PMCID: PMC11060135 DOI: 10.1146/annurev-pharmtox-010715-103335] [Citation(s) in RCA: 267] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mitochondria have emerged as key participants in and regulators of myocardial injury during ischemia and reperfusion. This review examines the sites of damage to cardiac mitochondria during ischemia and focuses on the impact of these defects. The concept that mitochondrial damage during ischemia leads to cardiac injury during reperfusion is addressed. The mechanisms that translate ischemic mitochondrial injury into cellular damage, during both ischemia and early reperfusion, are examined. Next, we discuss strategies that modulate and counteract these mechanisms of mitochondrial-driven injury. The new concept that mitochondria are not merely stochastic sites of oxidative and calcium-mediated injury but that they activate cellular responses of mitochondrial remodeling and cellular reactions that modulate the balance between cell death and recovery is reviewed, and the therapeutic implications of this concept are discussed.
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Affiliation(s)
- Edward J Lesnefsky
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia 23298; ,
- Medical Service, McGuire Veterans Affairs Medical Center, Richmond, Virginia 23249;
| | - Qun Chen
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University, Richmond, Virginia 23298; ,
| | - Bernard Tandler
- Department of Biological Sciences, Case Western Reserve University School of Dental Medicine, Cleveland, Ohio 44106;
| | - Charles L Hoppel
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106;
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
- Center for Mitochondrial Disease, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
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Wojtovich AP, Smith CO, Haynes CM, Nehrke KW, Brookes PS. Physiological consequences of complex II inhibition for aging, disease, and the mKATP channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:598-611. [PMID: 23291191 DOI: 10.1016/j.bbabio.2012.12.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 12/14/2012] [Accepted: 12/17/2012] [Indexed: 12/21/2022]
Abstract
In recent years, it has become apparent that there exist several roles for respiratory complex II beyond metabolism. These include: (i) succinate signaling, (ii) reactive oxygen species (ROS) generation, (iii) ischemic preconditioning, (iv) various disease states and aging, and (v) a role in the function of the mitochondrial ATP-sensitive K(+) (mKATP) channel. This review will address the involvement of complex II in each of these areas, with a focus on how complex II regulates or may be involved in the assembly of the mKATP. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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Affiliation(s)
- Andrew P Wojtovich
- Department of Medicine, University of Rochester Medical Center, Rochester, NY, USA
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Mourmoura E, Leguen M, Dubouchaud H, Couturier K, Vitiello D, Lafond JL, Richardson M, Leverve X, Demaison L. Middle age aggravates myocardial ischemia through surprising upholding of complex II activity, oxidative stress, and reduced coronary perfusion. AGE (DORDRECHT, NETHERLANDS) 2011; 33:321-36. [PMID: 20878490 PMCID: PMC3168590 DOI: 10.1007/s11357-010-9186-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Accepted: 09/14/2010] [Indexed: 05/04/2023]
Abstract
Aging compromises restoration of the cardiac mechanical function during reperfusion. We hypothesized that this was due to an ampler release of mitochondrial reactive oxygen species (ROS). This study aimed at characterising ex vivo the mitochondrial ROS release during reperfusion in isolated perfused hearts of middle-aged rats. Causes and consequences on myocardial function of the observed changes were then evaluated. The hearts of rats aged 10- or 52-week old were subjected to global ischemia followed by reperfusion. Mechanical function was monitored throughout the entire procedure. Activities of the respiratory chain complexes and the ratio of aconitase to fumarase activities were determined before ischemia and at the end of reperfusion. H(2)O(2) release was also evaluated in isolated mitochondria. During ischemia, middle-aged hearts displayed a delayed contracture, suggesting a maintained ATP production but also an increased metabolic proton production. Restoration of the mechanical function during reperfusion was however reduced in the middle-aged hearts, due to lower recovery of the coronary flow associated with higher mitochondrial oxidative stress indicated by the aconitase to fumarase ratio in the cardiac tissues. Surprisingly, activity of the respiratory chain complex II was better maintained in the hearts of middle-aged animals, probably because of an enhanced preservation of its membrane lipid environment. This can explain the higher mitochondrial oxidative stress observed in these conditions, since cardiac mitochondria produce much more H(2)O(2) when they oxidize FADH(2)-linked substrates than when they use NADH-linked substrates. In conclusion, the lower restoration of the cardiac mechanical activity during reperfusion in the middle-aged hearts was due to an impaired recovery of the coronary flow and an insufficient oxygen supply. The deterioration of the coronary perfusion was explained by an increased mitochondrial ROS release related to the preservation of complex II activity during reperfusion.
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Affiliation(s)
- Evangelia Mourmoura
- Laboratoire de Bioénergétique Fondamentale et Appliquée, INSERM U884, Université Joseph Fourier, BP 53, Grenoble Cedex 09, 38041 France
- Université Joseph Fourier, Laboratoire de Bioénergétique Fondamentale et Appliquée, Grenoble Cedex 09, 38041 France
| | - Marie Leguen
- Laboratoire de Bioénergétique Fondamentale et Appliquée, INSERM U884, Université Joseph Fourier, BP 53, Grenoble Cedex 09, 38041 France
- Université Joseph Fourier, Laboratoire de Bioénergétique Fondamentale et Appliquée, Grenoble Cedex 09, 38041 France
| | - Hervé Dubouchaud
- Laboratoire de Bioénergétique Fondamentale et Appliquée, INSERM U884, Université Joseph Fourier, BP 53, Grenoble Cedex 09, 38041 France
- Université Joseph Fourier, Laboratoire de Bioénergétique Fondamentale et Appliquée, Grenoble Cedex 09, 38041 France
| | - Karine Couturier
- Laboratoire de Bioénergétique Fondamentale et Appliquée, INSERM U884, Université Joseph Fourier, BP 53, Grenoble Cedex 09, 38041 France
- Université Joseph Fourier, Laboratoire de Bioénergétique Fondamentale et Appliquée, Grenoble Cedex 09, 38041 France
| | - Damien Vitiello
- Laboratoire de Bioénergétique Fondamentale et Appliquée, INSERM U884, Université Joseph Fourier, BP 53, Grenoble Cedex 09, 38041 France
- Université Joseph Fourier, Laboratoire de Bioénergétique Fondamentale et Appliquée, Grenoble Cedex 09, 38041 France
| | - Jean-Luc Lafond
- Département de Biologie Intégrée, CHU de Grenoble, Grenoble Cedex 09, 38043 France
| | - Melanie Richardson
- Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53705 USA
| | - Xavier Leverve
- Laboratoire de Bioénergétique Fondamentale et Appliquée, INSERM U884, Université Joseph Fourier, BP 53, Grenoble Cedex 09, 38041 France
- Université Joseph Fourier, Laboratoire de Bioénergétique Fondamentale et Appliquée, Grenoble Cedex 09, 38041 France
| | - Luc Demaison
- Laboratoire de Bioénergétique Fondamentale et Appliquée, INSERM U884, Université Joseph Fourier, BP 53, Grenoble Cedex 09, 38041 France
- Université Joseph Fourier, Laboratoire de Bioénergétique Fondamentale et Appliquée, Grenoble Cedex 09, 38041 France
- INRA, Unité CSGA, Dijon Cedex, 21065 France
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Guillet V, Gueguen N, Cartoni R, Chevrollier A, Desquiret V, Angebault C, Amati-Bonneau P, Procaccio V, Bonneau D, Martinou JC, Reynier P. Bioenergetic defect associated with mK
ATP
channel opening in a mouse model carrying a mitofusin 2 mutation. FASEB J 2011; 25:1618-27. [DOI: 10.1096/fj.10-173609] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Virginie Guillet
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- School of MedicineUniversity of AngersAngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Naïg Gueguen
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Romain Cartoni
- Department of Cell BiologyUniversity of GenevaGenevaSwitzerland
- F. M. Kirby Neurobiology CenterChildren's HospitalBostonMassachusettsUSA
- Department of NeurologyHarvard Medical SchoolBostonMassachusettsUSA
| | - Arnaud Chevrollier
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Valérie Desquiret
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Claire Angebault
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- School of MedicineUniversity of AngersAngersFrance
| | - Patrizia Amati-Bonneau
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Vincent Procaccio
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- School of MedicineUniversity of AngersAngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | - Dominique Bonneau
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- School of MedicineUniversity of AngersAngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
| | | | - Pascal Reynier
- Unité Mixte de Recherche (UMR) Centre National de la Recherche Scientifique (CNRS) 6214Institut National de la Santé et de la Recherche Médicale (INSERM) U771AngersFrance
- School of MedicineUniversity of AngersAngersFrance
- Department of Biochemistry and GeneticsUniversity Hospital of AngersAngersFrance
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Preconditioning with diazoxide prevents reoxygenation-induced rigor-type hypercontracture. J Mol Cell Cardiol 2010; 48:270-6. [DOI: 10.1016/j.yjmcc.2009.04.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 04/20/2009] [Accepted: 04/21/2009] [Indexed: 11/18/2022]
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7
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Cardioprotection by metabolic shut-down and gradual wake-up. J Mol Cell Cardiol 2009; 46:804-10. [PMID: 19285082 DOI: 10.1016/j.yjmcc.2009.02.026] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 02/26/2009] [Accepted: 02/27/2009] [Indexed: 10/21/2022]
Abstract
Mitochondria play a critical role in cardiac function, and are also increasingly recognized as end effectors for various cardioprotective signaling pathways. Mitochondria use oxygen as a substrate, so by default their respiration is inhibited during hypoxia/ischemia. However, at reperfusion a surge of oxygen and metabolic substrates into the cell is thought to lead to rapid reestablishment of respiration, a burst of reactive oxygen species (ROS) generation and mitochondrial Ca(2+) overload. Subsequently these events precipitate opening of the mitochondrial permeability transition (PT) pore, which leads to myocardial cell death and dysfunction. Given that mitochondrial respiration is already inhibited during hypoxia/ischemia, it is somewhat surprising that many respiratory inhibitors can improve recovery from ischemia-reperfusion (IR) injury. In addition ischemic preconditioning (IPC), in which short non-lethal cycles of IR can protect against subsequent prolonged IR injury, is known to lead to endogenous inhibition of several respiratory complexes and glycolysis. This has led to a hypothesis that the wash-out of inhibitors or reversal of endogenous inhibition at reperfusion may afford protection by facilitating a more gradual wake-up of mitochondrial function, thereby avoiding a burst of ROS and Ca(2+) overload. This paper will review the evidence in support of this hypothesis, with a focus on inhibition of each of the mitochondrial respiratory complexes.
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8
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Wojtovich AP, Brookes PS. The complex II inhibitor atpenin A5 protects against cardiac ischemia-reperfusion injury via activation of mitochondrial KATP channels. Basic Res Cardiol 2009; 104:121-9. [PMID: 19242645 DOI: 10.1007/s00395-009-0001-y] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 01/12/2009] [Accepted: 01/18/2009] [Indexed: 12/18/2022]
Abstract
The cardioprotective effects of ischemic preconditioning (IPC) can be mimicked or blocked by pharmacologic agents, which modulate the mitochondrial ATP-sensitive potassium (mK(ATP)) channel, thereby implicating this channel in the mechanism of IPC. Cardioprotection can also be achieved via inhibition of mitochondrial respiratory complex II, and significant pharmacologic overlap exists between complex II inhibitors and mK(ATP) channel agonists. However, the relationship between complex II and the mK(ATP) channel remains unclear. Atpenin A5 (AA5) is a potent and specific complex II inhibitor, and herein we report that AA5 (1 nM) also activates the mK(ATP) channel and protects against simulated ischemia-reperfusion (IR) injury in isolated cardiomyocytes. Similar to known mK(ATP) agonists, AA5-mediated protection was sensitive to the mK(ATP) antagonists 5-hydroxydecanoate (5HD) and glyburide. Notably, the optimal mK(ATP) opening and protective concentration of AA5 had no effect on complex II enzymatic activity, suggesting an interaction of AA5 with complex II, but not inhibition of the complex per se, is necessary for protection. A cardioprotective effect of AA5 was also observed in isolated perfused hearts, wherein AA5 increased post-IR contractile function and decreased infarct size, in a 5HD-sensitive manner. In conclusion, the specific complex II inhibitor AA5 is the most potent mK(ATP) activator discovered to date, and provides a novel method of activating mK(ATP) channels and protecting the heart from IR injury.
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Affiliation(s)
- Andrew P Wojtovich
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
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Grossini E, Molinari C, Caimmi PP, Uberti F, Vacca G. Levosimendan induces NO production through p38 MAPK, ERK and Akt in porcine coronary endothelial cells: role for mitochondrial K(ATP) channel. Br J Pharmacol 2009; 156:250-61. [PMID: 19154424 DOI: 10.1111/j.1476-5381.2008.00024.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Levosimendan acts as a vasodilator through the opening of ATP-sensitive K(+) channels (K(ATP)) channels. Moreover, the coronary vasodilatation caused by levosimendan in anaesthetized pigs has recently been found to be abolished by the nitric oxide synthase (NOS) inhibitor N(omega)-nitro-L-arginine methyl ester, indicating that nitric oxide (NO) has a role in the vascular effects of levosimendan. However, the intracellular pathway leading to NO production caused by levosimendan has not yet been investigated. Thus, the purpose of the present study was to examine the effects of levosimendan on NO production and to evaluate the intracellular signalling pathway involved. EXPERIMENTAL APPROACH In porcine coronary endothelial cells (CEC), the release of NO in response to levosimendan was examined in the presence and absence of N(omega)-nitro-L-arginine methyl ester, an adenylyl cyclase inhibitor, K(ATP) channel agonists and antagonists, and inhibitors of intracellular protein kinases. In addition, the role of Akt, ERK, p38 and eNOS was investigated through Western blot analysis. KEY RESULTS Levosimendan caused a concentration-dependent and K(+)-related increase of NO production. This effect was amplified by the mitochondrial K(ATP) channel agonist, but not by the selective plasma membrane K(ATP) channel agonist. The response of CEC to levosimendan was prevented by the K(ATP) channel blockers, the adenylyl cyclase inhibitor and the Akt, ERK, p38 inhibitors. Western blot analysis showed that phosphorylation of the above kinases lead to eNOS activation. CONCLUSIONS AND IMPLICATIONS In CEC levosimendan induced eNOS-dependent NO production through Akt, ERK and p38. This intracellular pathway is associated with the opening of mitochondrial K(ATP) channels and involves cAMP.
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Affiliation(s)
- E Grossini
- Laboratorio di Fisiologia, Dipartimento di Medicina Clinica e Sperimentale, Facoltà di Medicina e Chirurgia, Università del Piemonte Orientale A. Avogadro, via Solaroli 17, Novara, Italy.
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10
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Iijima T, Tanaka K, Matsubara S, Kawakami H, Mishima T, Suga K, Akagawa K, Iwao Y. Calcium loading capacity and morphological changes in mitochondria in an ischemic preconditioned model. Neurosci Lett 2008; 448:268-72. [PMID: 18955111 DOI: 10.1016/j.neulet.2008.10.056] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Revised: 10/16/2008] [Accepted: 10/17/2008] [Indexed: 01/25/2023]
Abstract
The concept of the mitochondrial permeability transition (mPT) has been used to explain cell death induced by calcium deregulation, which is in turn induced by a disruption in the mitochondrial loading capacity of cytosolic calcium (CLC). Whether mitochondria have specific morphologies representing the CLC and the mPT remains controversial. We examined ultrastructural changes in the mitochondria of cultured hippocampal neurons preconditioned with oxygen-glucose deprivation (OGD) for 30 min (30OGD) or 120 min (120OGD). The CLC was then evaluated using simultaneous imaging of the mitochondrial and plasma Ca++ concentrations after the induction of Ca++ influx by the application of glutamate. In the 30OGD group, the CLC increased as the mitochondria rapidly reacted to the increase in plasma Ca++, which was soon cleared. In the 120OGD group, however, the CLC was disturbed because the mitochondrial uptake of Ca was blunted, and the plasma Ca++ was not cleared after glutamate application. We classified the specific morphological changes in the mitochondria according to a previously reported classification. Rounded mitochondria with scarce interior content were observed in the 120OGD group, a model of prolonged lethal OGD, and disruptions in the mitochondrial outer membrane were frequently confirmed, suggesting mPT. The 30OGD group, a model of enhanced CLC in preconditioned neurons, was characterized by round mitochondria with condensed matrices. After glutamate application, the mitochondria became even more rounded with expanded matrices, and outer membrane disruptions were occasionally seen. Our observations suggest that subpopulations of mitochondria with specific morphologies are linked to the CLC and mPT.
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Affiliation(s)
- Takehiko Iijima
- Department of Anesthesiology, Kyorin University, School of Medicine, Japan.
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11
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Wojtovich AP, Brookes PS. The endogenous mitochondrial complex II inhibitor malonate regulates mitochondrial ATP-sensitive potassium channels: implications for ischemic preconditioning. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:882-9. [PMID: 18433712 DOI: 10.1016/j.bbabio.2008.03.025] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 03/19/2008] [Accepted: 03/25/2008] [Indexed: 11/17/2022]
Abstract
Ischemic preconditioning (IPC) affords cardioprotection against ischemia-reperfusion (IR) injury, and while the molecular mechanisms of IPC are debated, the mitochondrial ATP-sensitive K(+) channel (mK(ATP)) has emerged as a candidate effector for several IPC signaling pathways. The molecular identity of this channel is unknown, but significant pharmacologic overlap exists between mK(ATP) and mitochondrial respiratory complex II (succinate dehydrogenase). In this investigation, we utilized isolated cardiac mitochondria, Langendorff perfused hearts, and a variety of biochemical methods, to make the following observations: (i) The competitive complex II inhibitor malonate is formed in mitochondria under conditions resembling IPC. (ii) IPC leads to a reversible inhibition of complex II that has likely been missed in previous investigations due to the use of saturating concentrations of succinate. (iii) Malonate opens mK(ATP) channels even when mitochondria are respiring on complex I-linked substrates, suggesting an effect of this inhibitor on the mK(ATP) channel independent of complex II inhibition. Together, these observations suggest that complex II inhibition by endogenously formed malonate may represent an important activation pathway for mK(ATP) channels during IPC.
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Affiliation(s)
- Andrew P Wojtovich
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
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12
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Pasdois P, Beauvoit B, Tariosse L, Vinassa B, Bonoron-Adèle S, Dos Santos P. Effect of diazoxide on flavoprotein oxidation and reactive oxygen species generation during ischemia-reperfusion: a study on Langendorff-perfused rat hearts using optic fibers. Am J Physiol Heart Circ Physiol 2008; 294:H2088-97. [PMID: 18296562 DOI: 10.1152/ajpheart.01345.2007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study analyzed the oxidant generation during ischemia-reperfusion protocols of Langendorff-perfused rat hearts, preconditioned with a mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) opener (i.e., diazoxide). The autofluorescence of mitochondrial flavoproteins, and that of the total NAD(P)H pool on the one hand and the fluorescence of dyes sensitive to H(2)O(2) or O(2)(*-) [i.e., the dihydrodichlorofluoroscein (H(2)DCF) and dihydroethidine (DHE), respectively] on the other, were noninvasively measured at the surface of the left ventricular wall by means of optic fibers. Isolated perfused rat hearts were subjected to an ischemia-reperfusion protocol. Opening mitoK(ATP) with diazoxide (100 microM) 1) improved the recovery of the rate-pressure product after reperfusion (72 +/- 2 vs. 16.8 +/- 2.5% of baseline value in control group, P < 0.01), and 2) attenuated the oxidant generation during both ischemic (-46 +/- 5% H(2)DCF oxidation and -40 +/- 3% DHE oxidation vs. control group, P < 0.01) and reperfusion (-26 +/- 2% H(2)DCF oxidation and -23 +/- 2% DHE oxidation vs. control group, P < 0.01) periods. All of these effects were abolished by coperfusion of 5-hydroxydecanoic acid (500 microM), a mitoK(ATP) blocker. During the preconditioning phase, diazoxide induced a transient, reversible, and 5-hydroxydecanoic acid-sensitive flavoprotein and H(2)DCF (but not DHE) oxidation. In conclusion, the diazoxide-mediated cardioprotection is supported by a moderate H(2)O(2) production during the preconditioning phase and a strong decrease in oxidant generation during the subsequent ischemic and reperfusion phases.
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13
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Lynn EG, Lu Z, Minerbi D, Sack MN. The regulation, control, and consequences of mitochondrial oxygen utilization and disposition in the heart and skeletal muscle during hypoxia. Antioxid Redox Signal 2007; 9:1353-61. [PMID: 17627469 DOI: 10.1089/ars.2007.1700] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The major oxygen-dependent function of mitochondria partitions molecular oxygen between oxidative phosphorylation and reactive oxygen species generation. When oxygen becomes limiting, the modulation of mitochondrial function plays an important role in overall biologic adaptation. This review focuses on mitochondrial biology in the heart and skeletal muscle during hypoxia. The disparate mitochondrial responses discussed appear to be dependent on the degree of hypoxia, on the age at exposure to hypoxia, and on the duration of exposure. These hypoxia-induced changes include modulation in mitochondrial respiratory capacity; activation of the mitochondrial biogenesis regulatory program; induction of mitochondrial antioxidant defense systems; regulation of antiapoptotic mitochondrial proteins, and modulation of mitochondrial sensitivity to permeability transition. The mitochondria-derived reactive oxygen species signal-transduction events in response to hypoxia also are reviewed. The cardiac and skeletal muscle phenotypic signatures that result from mitochondrial adaptations include an amelioration of resistance to cardiac ischemia and modulations in exercise capacity and oxidative fuel preference. Overall, the data demonstrate the plasticity in mitochondrial regulation and function that facilitates adaptations to a limited oxygen supply. Moreover, data supporting the role of mitochondria as oxygen-sensing organelles, integrated into global cellular signal transduction are discussed.
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Affiliation(s)
- Edward G Lynn
- Cardiology Branch, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-1454, USA
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