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Nitric oxide as a cellular antioxidant: A little goes a long way
Journal article   Peer reviewed

Nitric oxide as a cellular antioxidant: A little goes a long way

Stephen G Hummel, Anthony J Fischer, Sean M Martin, Freya Q Schafer and Garry R Buettner
Free radical biology & medicine, Vol.40(3), pp.501-506
2006
DOI: 10.1016/j.freeradbiomed.2005.08.047
PMCID: PMC2258411
PMID: 16443165

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Abstract

Nitric oxide (NO ) is an effective chain-breaking antioxidant in free radical-mediated lipid oxidation (LPO). It reacts rapidly with peroxyl radicals as a sacrificial chain-terminating antioxidant. The goal of this work was to determine the minimum threshold concentration of NO required to inhibit Fe 2+-induced cellular lipid peroxidation. Using oxygen consumption as a measure of LPO, we simultaneously measured nitric oxide and oxygen concentrations with NO and O 2 electrodes. Ferrous iron and dioxygen were used to initiate LPO in docosahexaenoic acid-enriched HL-60 and U937 cells. Bolus addition of NO (1.5 μM) inhibited LPO when the NO concentration was greater than 50 nM. Similarly, using ( Z)-1-[ N-(3-ammoniopropyl)- N-( n-propyl)amino]diazen-1-ium-1,2-diolate as a NO donor we found that an average steady-state NO concentration of at least 72 ± 9 nM was required to blunt LPO. As long as the concentration of NO was above 13 ± 8 nM the inhibition was sustained. Once the concentration of NO fell below this value, the rate of lipid oxidation accelerated as measured by the rate of oxygen consumption. Our model suggests that a continuous production of NO that would yield a steady-state concentration of only 10–20 nM is capable of inhibiting Fe 2+-induced LPO.
 Nitric oxide Lipid peroxidation Oxygen consumption Iron HL-60 Antioxidant Free radical U937

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