title: Formation of hydrogen peroxide and reduction of peroxynitrite via dismutation of superoxide at reperfusion enhances myocardial blood flow and oxygen consumption in postischemic mouse heart.
abstract: Reactive oxygen/nitrogen species suppress myocardial oxygen consumption. In this study, we determined that endogenous hydrogen peroxide through dismutation of superoxide enhances postischemic myocardial blood perfusion and oxygen consumption. Electron paramagnetic resonance oximetry was applied to monitor in vivo tissue Po2 in mouse heart subjected to regional ischemia reperfusion. Heart rate, arterial blood pressure, blood flow, infarction, and activities of mitochondrial NADH dehydrogenase and cytochrome c oxidase were measured in six groups of wild-type (WT) and endothelial nitricoxide synthase knock-out (eNOS(-/-)) mice treated with phosphate-buffered saline (PBS), superoxide dismutase mimetic (SOD(m)) M40403 [a manganese(II)-bis(cyclohexylpyridine)-substituted macrocyclic superoxide dismutase mimetic, C21H35Cl2MnN5], 10006329 EUK 134 [EUK134, manganese 3-methoxy N,N(1)-bis(salicyclidene)ethylenediamine chloride], and SOD(m) plus glibenclamide to study the protective effect of hydrogen peroxide via dismutation of superoxide on the activation of sarcolemmal potassium channels. In the PBS group, there was an overshoot of tissue Po2 after reperfusion. Treatment with SOD(m), EUK134, and SOD(m) + glibenclamide protected mitochondrial enzyme activities, reduced infarct size, and suppressed the postischemic hyperoxygenation. In particular, in the SOD(m)-treated group, there was a transient peak of tissue Po2 at 9 min after reperfusion, which was dependent on endogenous hydrogen peroxide but not nitric oxide formation as it appeared in both WT and eNOS(-/-) mice. Blood flow and rate pressure product were higher in the SOD(m) group than in other groups, which contributed to the transient oxygen peak. Thus, SOD mimetics protected mouse heart from superoxide-induced reperfusion injury. With treatment of different SOD mimetics, it is concluded that endogenous hydrogen peroxide via dismutation of superoxide at reperfusion enhances postischemic myocardial blood perfusion and mitochondrial oxygen consumption, possibly through activation of sarcolemmal ATP-sensitive potassium channels.
authors.affiliation: The Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, and Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xu
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Jay L
authors.initials: JL
authors.lastname: Zweier
authors.forename: Guanglong
authors.initials: G
authors.lastname: He
mesh_terms: D000818:Animals; D003326:Coronary Circulation; D004578:Electron Spin Resonance Spectroscopy; D005905:Glyburide / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism*; D054086:KATP Channels / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017202:Myocardial Ischemia / Q000378:metabolism*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000502:physiology; D052250:Nitric Oxide Synthase Type III; D009942:Organometallic Compounds / Q000494:pharmacology; D010092:Oximetry; D010101:Oxygen Consumption; D030421:Peroxynitrous Acid / Q000378:metabolism*; D012459:Salicylates / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000502:physiology*
chemical_list: C433928:EUK-134; D054086:KATP Channels; D009942:Organometallic Compounds; D012459:Salicylates; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D013482:Superoxide Dismutase; D005905:Glyburide