Shiva, S. et al. Nitrite augments tolerance to ischemia/reperfusion injury via the modulation of mitochondrial electron transfer. J. Exp. Med. 204, 2089-2102

Vascular Medicine Branch, National Heart Lung Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Journal of Experimental Medicine (Impact Factor: 13.91). 10/2007; 204(9):2089-102. DOI: 10.1084/jem.20070198
Source: PubMed

ABSTRACT Nitrite (NO(2)(-)) is an intrinsic signaling molecule that is reduced to NO during ischemia and limits apoptosis and cytotoxicity at reperfusion in the mammalian heart, liver, and brain. Although the mechanism of nitrite-mediated cytoprotection is unknown, NO is a mediator of the ischemic preconditioning cell-survival program. Analogous to the temporally distinct acute and delayed ischemic preconditioning cytoprotective phenotypes, we report that both acute and delayed (24 h before ischemia) exposure to physiological concentrations of nitrite, given both systemically or orally, potently limits cardiac and hepatic reperfusion injury. This cytoprotection is associated with increases in mitochondrial oxidative phosphorylation. Remarkably, isolated mitochondria subjected to 30 min of anoxia followed by reoxygenation were directly protected by nitrite administered both in vitro during anoxia or in vivo 24 h before mitochondrial isolation. Mechanistically, nitrite dose-dependently modifies and inhibits complex I by posttranslational S-nitrosation; this dampens electron transfer and effectively reduces reperfusion reactive oxygen species generation and ameliorates oxidative inactivation of complexes II-IV and aconitase, thus preventing mitochondrial permeability transition pore opening and cytochrome c release. These data suggest that nitrite dynamically modulates mitochondrial resilience to reperfusion injury and may represent an effector of the cell-survival program of ischemic preconditioning and the Mediterranean diet.

Download full-text


Available from: Sruti Shiva, Aug 20, 2015
  • Source
    • "Importantly, the impairment of ETC was directly confirmed by enzyme activity measurements that revealed a greatly reduced complex I activity (Fig. 4D), consistent with previous studies in mitochondria from hypoxia-sensitive species (da Silva et al., 2003; Heerlein et al., 2005; Galkin et al., 2009) that implicated a role of complex I in hypoxia/reoxygenation-induced dysfunction. Irrespective of the cause, the quintessential effect of complex I inhibition is leakage of electrons from the ETC leading to increased production of ROS (Raha et al., 2000; Turrens, 2003; Galkin and Brandt, 2005; Shiva et al., 2007; Fato et al., 2009; Murphy, 2009), with oxidative damage of not only the enzyme itself but also other mitochondrial components. We therefore tested the hypothesis that inhibition of complex-I-driven state 3 respiration was mediated by oxidative damage following over-production of ROS after hypoxia/ reoxygenation. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The goal of the present study was to elucidate the modulatory effects of cadmium (Cd) on hypoxia-reoxygenation-induced mitochondrial dysfunction in light of the limited understanding of the mechanisms of multiple stressor interactions in aquatic organisms. Rainbow trout (Oncorhynchus mykiss) liver mitochondria were isolated and energized with complex I substrates, malate-glutamate, and exposed to hypoxia (0>PO2 <2 torr) for 0-60 min followed by reoxygenation and measurement of coupled and uncoupled respiration and complex I enzyme activity. Thereafter, 5 min hypoxia was used to probe interactions with cadmium (Cd) (0-20 µM) and to test the hypothesis that deleterious effects of hypoxia-reoxygenation on mitochondria were mediated by reactive oxygen species (ROS). Hypoxia-reoxygenation inhibited state 3 and uncoupler-stimulated (state 3u) respiration while concomitantly stimulating state 4 and 4ol (proton leak) respirations, thus reducing phosphorylation and coupling efficiencies. Low doses of Cd (≤ 5 µM) reduced, while higher doses enhanced, hypoxia-stimulated proton leak. This was in contrast to the monotonic enhancement by Cd of hypoxia-reoxygenation-induced reductions of state 3 respiration, phosphorylation efficiency and coupling. Mitochondrial complex I activity was inhibited by hypoxia-reoxygenation, hence confirming the impairment of at least one component of the electron transport chain (ETC) in rainbow trout mitochondria. Similar to the effect on state 4 and proton leak, low doses of Cd partially reversed the hypoxia-reoxygenation-induced complex I activity inhibition. The ROS scavenger and sulfhydryl group donor, N-acetylcysteine (NAC), administrated immediately prior to hypoxia exposure, reduced hypoxia-reoxygenation-stimulated proton leak without rescuing the inhibited state 3 respiration suggesting that hypoxia-reoxygenation influences distinct aspects of mitochondria via different mechanisms. Our results indicate that hypoxia-reoxygenation impairs the ETC and sensitizes mitochondria to Cd via mechanisms that involve, at least in part, ROS. Moreover we provide, for the first time in fish, evidence for hormetic effect of Cd on mitochondrial bioenergetics -the attenuation of hypoxia-reoxygenation-stimulated proton leak and partial rescue of complex I inhibition by low Cd doses.
    Journal of Experimental Biology 11/2013; 217(6). DOI:10.1242/jeb.093344 · 3.00 Impact Factor
  • Source
    • "This dampens electron transfer and reduces reactive oxygen species generation and ameliorates oxidative inactivation of complexes II–IV and aconitase. This prevents mitochondrial permeability transition pore opening and cytochrome c release (Shiva et al., 2007). Another potential mechanism of nitrite-induced protection relates to the modification of the mitochondrial permeability transition pore (MPTP) opening, which plays a critical role in mediating cell death during ischaemia/reperfusion injury. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In the last decade, the nitrate-nitrite-nitric oxide (NO) pathway has emerged to therapeutical importance. Modulation of endogenous nitrate and nitrite levels with the subsequent S-nitros(yl)ation of the downstream signalling cascade open the way for novel cytoprotective strategies. In the following we summarize the actual literature and give a short overview on the potential of nitrite in organ protection.
    British Journal of Pharmacology 07/2013; 171. DOI:10.1111/bph.12291 · 4.99 Impact Factor
  • Source
    • "In animal studies, dietary nitrate or nitrite protect against ischaemia–reperfusion injury in the heart (Duranski et al, 2005), liver (Duranski et al, 2005), brain (Jung et al, 2006), kidney (Carlstrom et al, 2011) and skeletal muscle (Kumar et al, 2008). The exact mechanism(s) has not yet been pinpointed and probably varies in different organs, but a reversible inhibition of complex I in the mitochondrial respiratory chain, leading to reduced generation of oxygen radicals as well as less apoptosis, has been suggested (Shiva et al, 2007b). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The tiny radical nitric oxide (NO) participates in a vast number of physiological functions including vasodilation, nerve transmission, host defence and cellular energetics. Classically produced by a family of specific enzymes, NO synthases (NOSs), NO signals via reactions with other radicals or transition metals. An alternative pathway for the generation of NO is the nitrate-nitrite-NO pathway in which the inorganic anions nitrate (NO3-) and nitrite (NO2-) are reduced to NO and other reactive nitrogen intermediates. Nitrate and nitrite are oxidation products from NOS-dependent NO generation but also constituents in our diet, mainly in leafy green vegetables. Irrespective of origin, active uptake of circulating nitrate in the salivary glands, excretion in saliva and subsequent reduction to nitrite by oral commensal bacteria are all necessary steps for further NO generation. This central role of the oral cavity in regulating NO generation from nitrate presents a new and intriguing aspect of the human microbiome in health and disease. In this review, we present recent advances in our understanding of the nitrate-nitrite-NO pathway and specifically highlight the importance of the oral cavity as a hub for its function.
    Oral Diseases 06/2013; 21(1). DOI:10.1111/odi.12157 · 2.40 Impact Factor
Show more