title: Mitochondrial uncoupling does not decrease reactive oxygen species production after ischemia-reperfusion.
abstract: Cardiac ischemia-reperfusion (IR) leads to myocardial dysfunction by increasing production of reactive oxygen species (ROS). Mitochondrial H(+) leak decreases ROS formation; it has been postulated that increasing H(+) leak may be a mechanism of decreasing ROS production after IR. Ischemic preconditioning (IPC) decreases ROS formation after IR, but the mechanism is unknown. We hypothesize that pharmacologically increasing mitochondrial H(+) leak would decrease ROS production after IR. We further hypothesize that IPC would be associated with an increase in the rate of H(+) leak. Isolated male Sprague-Dawley rat hearts were subjected to either control or IPC. Mitochondria were isolated at end equilibration, end ischemia, and end reperfusion. Mitochondrial membrane potential (mΔΨ) was measured using a tetraphenylphosphonium electrode. Mitochondrial uncoupling was achieved by adding increasing concentrations of FCCP. Mitochondrial ROS production was measured by fluorometry using Amplex-Red. Pyridine dinucleotide levels were measured using HPLC. Before IR, increasing H(+) leak decreased mitochondrial ROS production. After IR, ROS production was not affected by increasing H(+) leak. H(+) leak increased at end ischemia in control mitochondria. IPC mitochondria showed no change in the rate of H(+) leak throughout IR. NADPH levels decreased after IR in both IPC and control mitochondria while NADH increased. Pharmacologically, increasing H(+) leak is not a method of decreasing ROS production after IR. Replenishing the NADPH pool may be a means of scavenging the excess ROS thereby attenuating oxidative damage after IR.
authors.affiliation: Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio;
authors.forename: Ricardo
authors.initials: R
authors.lastname: Quarrie
authors.affiliation: Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio;
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Lee
authors.affiliation: The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio; and.
authors.forename: Levy
authors.initials: L
authors.lastname: Reyes
authors.affiliation: Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio.
authors.forename: Warren
authors.initials: W
authors.lastname: Erdahl
authors.affiliation: Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Pfeiffer
authors.affiliation: The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio; and Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio.
authors.forename: Jay L
authors.initials: JL
authors.lastname: Zweier
authors.affiliation: Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio; The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio; and juan.crestanello@osumc.edu.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Crestanello
mesh_terms: D000818:Animals; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D011522:Protons; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014475:Uncoupling Agents / Q000494:pharmacology*
chemical_list: D011522:Protons; D017382:Reactive Oxygen Species; D014475:Uncoupling Agents; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
keywords: ischemia-reperfusion; mitochondria; proton leak; reactive oxygen species; uncoupling
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