title: Mechanistic characterization of nitrite-mediated neuroprotection after experimental cardiac arrest.
abstract: Nitrite acts as an ischemic reservoir of nitric oxide (NO) and a potent S-nitrosating agent which reduced histologic brain injury after rat asphyxial cardiac arrest (ACA). The mechanism(s) of nitrite-mediated neuroprotection remain to be defined. We hypothesized that nitrite-mediated brain mitochondrial S-nitrosation accounts for neuroprotection by reducing reperfusion reactive oxygen species (ROS) generation. Nitrite (4 μmol) or placebo was infused IV after normothermic (37°C) ACA in randomized, blinded fashion with evaluation of neurologic function, survival, brain mitochondrial function, and ROS. Blood and CSF nitrite were quantified using reductive chemiluminescence and S-nitrosation by biotin switch. Direct neuroprotection was verified in vitro after 1 and 4 h neuronal oxygen glucose deprivation measuring neuronal death with inhibition studies to examine mechanism. Mitochondrial ROS generation was quantified by live neuronal imaging using mitoSOX. Nitrite significantly reduced neurologic disability after ACA. ROS generation was reduced in brain mitochondria from nitrite- versus placebo-treated rats after ACA with congruent preservation of brain ascorbate and reduction of ROS in brain sections using immuno-spin trapping. ATP generation was maintained with nitrite up to 24 h after ACA. Nitrite rapidly entered CSF and increased brain mitochondrial S-nitrosation. Nitrite reduced in vitro mitochondrial superoxide generation and improved survival of neurons after oxygen glucose deprivation. Protection was maintained with inhibition of soluble guanylate cyclase but lost with NO scavenging and ultraviolet irradiation. Nitrite therapy results in direct neuroprotection from ACA mediated by reductions in brain mitochondrial ROS in association with protein S-nitrosation. Neuroprotection is dependent on NO and S-nitrosothiol generation, not soluble guanylate cyclase.
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. dezfulianc@upmc.edu.|Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. dezfulianc@upmc.edu.|Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. dezfulianc@upmc.edu.
authors: Cameron
authors: C
authors: Dezfulian
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Elizabeth
authors: E
authors: Kenny
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Andrew
authors: A
authors: Lamade
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Amalea
authors: A
authors: Misse
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Nicholas
authors: N
authors: Krehel
authors: Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Claudette
authors: C
authors: St Croix
authors: Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Eric E
authors: EE
authors: Kelley
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Travis C
authors: TC
authors: Jackson
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Thomas
authors: T
authors: Uray
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Justin
authors: J
authors: Rackley
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Patrick M
authors: PM
authors: Kochanek
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Robert S B
authors: RS
authors: Clark
authors: Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|Department of Environmental and Occupational Health, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors: Hulya
authors: H
authors: Bayir
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D001237:Asphyxia / Q000503:physiopathology; D001923:Brain Chemistry; D002470:Cell Survival; D016166:Free Radical Scavengers / Q000494:pharmacology; D005947:Glucose / Q000172:deficiency; D006162:Guanylate Cyclase / Q000378:metabolism; D006323:Heart Arrest / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects; D000066829:Neuroprotection / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D016019:Survival Analysis
chemical_list: D016166:Free Radical Scavengers; D018696:Neuroprotective Agents; D009573:Nitrites; D017382:Reactive Oxygen Species; D013481:Superoxides; D009569:Nitric Oxide; D006162:Guanylate Cyclase; D005947:Glucose; D001205:Ascorbic Acid
keywords: cardiac arrest; cerebral ischemia; mitochondria; nitric oxide; reactive oxygen species; reperfusion injury