title: Pre-ischaemic mitochondrial substrate constraint by inhibition of malate-aspartate shuttle preserves mitochondrial function after ischaemia-reperfusion.
abstract: 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.
  
  
  
  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.
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Nichlas Riise
authors.initials: NR
authors.lastname: Jespersen
authors.affiliation: Xlab, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Takashi
authors.identifier: 0000-0001-5470-6648
authors.initials: T
authors.lastname: Yokota
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Nicolaj Brejnholt
authors.initials: NB
authors.lastname: Støttrup
authors.affiliation: Department of Exercise Science, Concordia University, Montreal, Canada.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bergdahl
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Kim Bolther
authors.initials: KB
authors.lastname: Paelestik
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Jonas Agerlund
authors.initials: JA
authors.lastname: Povlsen
authors.affiliation: Xlab, Center for Healthy Aging, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.|Department of Geriatrics, Bispebjerg University Hospital, Copenhagen, Denmark.
authors.forename: Flemming
authors.identifier: 0000-0001-9970-9535
authors.initials: F
authors.lastname: Dela
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Hans Erik
authors.initials: HE
authors.lastname: Bøtker
mesh_terms: D000625:Aminooxyacetic Acid / Q000494:pharmacology; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D002316:Cardiotonic Agents / Q000494:pharmacology; D019069:Cell Respiration / Q000187:drug effects; D002952:Citric Acid Cycle / Q000187:drug effects; D042967:Electron Transport Complex I / Q000378:metabolism; D006321:Heart / Q000187:drug effects; D008293:Malates / Q000378:metabolism*; D008297:Male; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D009203:Myocardial Infarction / Q000378:metabolism; D017202:Myocardial Ischemia / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D020011:Protective Agents / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D002316:Cardiotonic Agents; D008293:Malates; D020011:Protective Agents; D017382:Reactive Oxygen Species; D000625:Aminooxyacetic Acid; D001224:Aspartic Acid; D042967:Electron Transport Complex I
keywords: heart; ischemia-reperfusion; malate-aspartate shuttle; mitochondria; oxidative stress