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Dezfulian C, Kenny E, Lamade A, Misse A, Krehel N, St Croix C, Kelley EE, Jackson TC, Uray T, Rackley J, Kochanek PM, Clark RSB, Bayir H. Mechanistic characterization of nitrite-mediated neuroprotection after experimental cardiac arrest. J Neurochem 2016; 139:419-431. [PMID: 27507435 DOI: 10.1111/jnc.13764] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/04/2016] [Accepted: 08/05/2016] [Indexed: 12/27/2022]
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.
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Affiliation(s)
- Cameron Dezfulian
- 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. .,Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
| | - Elizabeth Kenny
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Andrew Lamade
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Amalea Misse
- 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
| | - Nicholas Krehel
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Claudette St Croix
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Eric E Kelley
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Travis C Jackson
- 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
| | - Thomas Uray
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Justin Rackley
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Patrick M Kochanek
- 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
| | - Robert S B Clark
- 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
| | - Hulya Bayir
- 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
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