title: Electron paramagnetic resonance oximetry and redoximetry.
abstract: Reactive oxygen/nitrogen species (ROS/RNS) have been increasingly recognized as important mediators and play a number of critical roles in cell injury, metabolism, disease pathology, diagnosis, and clinical treatment. Electron paramagnetic resonance (EPR) spectroscopy enables the spectral information at certain spatial position, and, from the observed line-width and signal intensity, the localized tissue oxygenation, and tissue redox status can be determined. We applied in vivo EPR oximetry and redoximetry technique and implemented its physiological/pathophysiological applications, along with the use of biocompatible lithium pthalocyanine (liPc) and nitroxide redox sensitive probes, on in vivo tissue oxygenation and redox profile of the ischemic and reperfused heart in living animals. We have observed that the hypoxia during myocardial ischemia limited mitochondrial respiration and caused a shift of tissue redox status to a more reduced state. ROS/RNS generated at the beginning of reperfusion not only caused a shift of redox status to a more oxidized state which may contribute to the postischemic myocardial injury, but also a marked suppression of in vivo tissue O(2) consumption in the postischemic heart through modulation of mitochondrial respiration based on alterations in enzyme activity and mRNA expression of NADH dehydrogenase (NADH-DH) and cytochrome c oxidase (CcO). In addition, ischemic preconditioning was found to be able to markedly attenuate postischemic myocardial hyperoxygenation with less ROS/RNS generation and preservation of mitochondrial O(2) metabolism, due to conserved NADH-DH and CcO activities. These studies have demonstrated that EPR oximetry and redoximetry techniques have advanced to a stage that enables in-depth insight in the process of ischemia reperfusion injury.
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, OH, USA. Guanglong.He@osumc.edu
authors.forename: Guanglong
authors.initials: G
authors.lastname: He
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D003576:Electron Transport Complex IV / Q000378:metabolism; D005609:Free Radicals / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D007150:Immunohistochemistry; D019194:Ischemic Preconditioning; D008297:Male; D051379:Mice; D009245:NADH Dehydrogenase / Q000378:metabolism; D010084:Oxidation-Reduction; D010092:Oximetry / Q000379:methods*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D005609:Free Radicals; C002744:3-nitrotyrosine; D014443:Tyrosine; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV; D005978:Glutathione; D019803:Glutathione Disulfide