Reactive oxygen species generated during myocardial ischemia enable energetic recovery during reperfusion

• Published in: American journal of physiology. Heart and circulatory physiology 2002-10, Vol.283 (4), p.H1656-H1661
• Main Authors: Klawitter, Paul F, Murray, Holt N, Clanton, Thomas L, Angelos, Mark G
• Format: Article
• Language: English
• Subjects: 1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt - pharmacology; Acetylcysteine - pharmacology; Adenosine Triphosphate - metabolism; Animals; Antioxidants - pharmacology; Deferoxamine - pharmacology; Energy Metabolism - drug effects; Energy Metabolism - physiology; Free Radical Scavengers - pharmacology; In Vitro Techniques; Iron Chelating Agents - pharmacology; Ischemic Preconditioning, Myocardial; Male; Myocardial Reperfusion; Myocardial Stunning - metabolism; Myocardium - metabolism; Oxidative Stress - drug effects; Oxidative Stress - physiology; Perfusion; Phosphocreatine - metabolism; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species - metabolism
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00041.2002

1  Department of Emergency Medicine and 2  Division of Pulmonary and Critical Care Medicine, The Ohio State University, Columbus, Ohio 43210 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. N -acetyl- L -cysteine; Tiron; efficiency; myocardial stunning