title: Nitric oxide produced in rat liver mitochondria causes oxidative stress and impairment of respiration after transient hypoxia.
abstract: Nitric oxide (NO) is produced in mammals by different isoforms of NO synthase (NOS), including the constitutive mitochondrial enzyme (mtNOS). Here we demonstrate that the concentration of NO resulting from a mitochondrial NOS activity increases under hypoxic conditions in isolated rat liver mitochondria. We show that mitochondrially derived NO mediates the impairment of active (state 3) respiration as measured in the presence of the substrates glutamate and malate after reoxygenation. Simultaneously, NO induces oxidative stress in mitochondria, characterized by an increase in the amount of protein carbonyls and a decrease in glutathione (GSH). Both the accumulation of oxidative stress markers during and the impaired respiration after reoxygenation were prevented by blocking NO production with the NOS inhibitor L-NAME. These observations suggest that mitochondria are exposed to high amounts of NO generated by a mitochondrial NOS upon hypoxia/reoxygenation. Such increased NO levels, in turn, inhibit mitochondrial respiration and may cause oxidative stress that leads to irreversible impairment of mitochondria.
authors.affiliation: Institute of Clinical Chemistry and Pathological Biochemistry, Department of Pathological Biochemistry, Otto-von-Guericke-University, Magdeburg, Germany. lorenz.schild@medizin.uni-magdeburg.de
authors.forename: Lorenz
authors.initials: L
authors.lastname: Schild
authors.forename: Thomas
authors.initials: T
authors.lastname: Reinheckel
authors.forename: Michael
authors.initials: M
authors.lastname: Reiser
authors.forename: Thomas F W
authors.initials: TF
authors.lastname: Horn
authors.forename: Gerald
authors.initials: G
authors.lastname: Wolf
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Augustin
mesh_terms: D000818:Animals; D015687:Cell Hypoxia; D019069:Cell Respiration; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D018384:Oxidative Stress; D010101:Oxygen Consumption; D051381:Rats
chemical_list: D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester