title: Reactive oxygen species generated during myocardial ischemia enable energetic recovery during reperfusion.
abstract: We studied the differences between the functional and bioenergetic effects of antioxidants (AOX) administered before or after myocardial ischemia. Sprague-Dawley rat hearts were perfused with a modified Krebs-Henseleit solution and bubbled with 95% O(2)-5% CO(2). The protocol consisted of 10 min of baseline perfusion, 20 min of global ischemia, and 30 min of reperfusion. An AOX, either 1,2-dihydroxybenzene-3,5-disulfonate (Tiron), a superoxide scavenger, or N-acetyl-L-cysteine, was infused during either baseline or reperfusion. An additional group received deferoxamine as a bolus before ischemia. Hearts were freeze-clamped at baseline, at end of ischemia, and at end of reperfusion for analysis of high-energy phosphates. All AOX, when given before ischemia, inhibited recovery of ATP compared with controls. Both Tiron and deferoxamine also inhibited recovery of phosphocreatine. AOX given before ischemia decreased the efficiency of contraction during reperfusion compared with controls. All of the changes in energetics and efficiency brought on by preischemic AOX treatment could be blocked by a preconditioning stimulus. This suggests that reactive oxygen species, which are generated during ischemia, enhance bioenergetic recovery by increasing the efficiency of contraction.
authors.affiliation: Department of Emergency Medicine, The Ohio State University, Columbus 43210, USA. Klawittp@upstate.edu
authors.forename: Paul F
authors.initials: PF
authors.lastname: Klawitter
authors.forename: Holt N
authors.initials: HN
authors.lastname: Murray
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Clanton
authors.forename: Mark G
authors.initials: MG
authors.lastname: Angelos
mesh_terms: D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt / Q000494:pharmacology; D000111:Acetylcysteine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D003676:Deferoxamine / Q000494:pharmacology; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D066298:In Vitro Techniques; D007502:Iron Chelating Agents / Q000494:pharmacology; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D015425:Myocardial Reperfusion; D017682:Myocardial Stunning / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010477:Perfusion; D010725:Phosphocreatine / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D007502:Iron Chelating Agents; D017382:Reactive Oxygen Species; D010725:Phosphocreatine; D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt; D000255:Adenosine Triphosphate; D003676:Deferoxamine; D000111:Acetylcysteine