Dungel 2013 Abstract MiP2013

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Dungel P, Perlinger M, Faulhammer B, Weidinger A, Redl H, Kozlov AV (2013) Iron-mediated injury of mitochondria is attenuated by nitrite. Mitochondr Physiol Network 18.08.
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Peter Dungel
MiP2013, Book of Abstracts Open Access

Dungel P, Perlinger M, Faulhammer B, Weidinger A, Redl H, Kozlov AV (2013)

Event: MiPNet18.08_MiP2013

Recently nitrite has been shown to protect various organs from ischemia-reperfusion injury, in particular ameliorates mitochondrial dysfunction. The mechanisms of protection, however, are still unclear. We aimed to investigate the impact of nitrite on mitochondrial damage mediated by free iron, a strong promoter of oxidative stress in an in vitro model of hypoxia/reoxygenation.

Isolated rat liver mitochondria were subjected to 15 min of hypoxia followed by 15 min of reoxygenation (H/R). Respiratory activity of mitochondria was monitored in an Oxygraph-2k (Oroboros Instruments). Dinitrosyl-iron-complexes (DNIC) and reactive oxygen species (ROS) were detected by electron paramagnetic resonance spectroscopy (EPR), the latter by using CMH, a hydroxylamine spin probe. Lipid peroxidation was assessed spectrophotometrically by determination of thiobarbituric acid reactive substances (TBARS).

H/R induced mitochondrial damage resulting in decreased respiration rates. Mitochondrial damage occurred predominantly during reoxygenation, accompanied by elevated ROS and TBARS levels. Exogenous Fe aggravated these changes in a concentration-dependent manner. Cytochrome c completely restored respiration with succinate but not with glutamate, suggesting two sites of damage in mitochondria, namely outer mitochondrial membrane and Complex I. Nitrite protected mitochondrial respiration and reduced TBARS levels but not ROS levels. This protective effect was accompanied by the formation of chemically inactive Fe-NO complexes. Iron chelators (desferoxamine, EDTA) protected mitochondria similar to nitrite manner.

Our data suggest that Fe directly, without intermediate ROS formation, induces damage to the outer mitochondrial membrane via activation of lipid peroxidation. Nitrite is reduced during hypoxia to NO, which scavenges free iron to form inactive NO-Fe complexes and thus, preventing damage to the outer mitochondrial membrane and cytochrome c release. The involvement of Complex I in the mechanisms of nitrite-mediated cytoprotection has to be further investigated.


O2k-Network Lab: AT Vienna Kozlov AV


Labels: MiParea: Respiration, mt-Membrane, mt-Medicine, Pharmacology;toxicology 

Stress:Ischemia-reperfusion, Oxidative stress;RONS  Organism: Rat  Tissue;cell: Liver  Preparation: Isolated mitochondria 

Regulation: Cyt c  Coupling state: OXPHOS  Pathway: N, S  HRR: Oxygraph-2k 

MiP2013, S10 

Affiliations and author contributions

Ludwig Boltzmann Inst. Experimental Clinical Traumatology, Vienna, Austria. - Email: peter.dungel@trauma.lbg.ac.at