Article: article from journal or magazin.
L-tyrosine and nitric oxide synergize to prevent cytotoxic effects of superoxide.
Publication types: Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, P.H.S. Souici A.C. a repris son nom Peyter, AC
We found previously that the nitric oxide donor DEA/NO enhanced lipid peroxidation, DNA fragmentation, and cytotoxicity in human bronchial epithelial cells (BEAS-2B) when they were cultured in LHC-8 medium containing the superoxide-generating system hypoxanthine/xanthine oxidase (HX/XO). We have now discovered that DEA/NO's prooxidant action can be reversed by raising the L-tyrosine concentration from 30 to 400 microM. DEA/NO also protected the cells when they were cultured in Dulbecco's Modified Eagle's Medium (DMEM), whose standard concentration of L-tyrosine is 400 microM. Similar trends were seen with the colon adenoma cell line CaCo-2. Since HPLC analysis of cell-free DMEM or LHC-8 containing 400 microM L-tyrosine, DEA/NO, and HX/XO revealed no evidence of L-tyrosine nitration, our data suggest the existence of an as-yet uncharacterized mechanism by which L-tyrosine can influence the biochemical and toxicological effects of reactive nitrogen species.
Bronchi/cytology, Bronchi/drug effects, Caco-2 Cells/drug effects, Cell Line, Cell Survival/drug effects, DNA Damage, Drug Synergism, Humans, Hydrazines/pharmacology, Hydrazines/toxicity, Hypoxanthine/metabolism, Lipid Peroxidation/drug effects, Nitric Oxide/pharmacology, Nitric Oxide/toxicity, Nitric Oxide Donors/pharmacology, Nitric Oxide Donors/toxicity, Nitrogen Oxides, Reactive Oxygen Species/metabolism, Superoxides/antagonists & inhibitors, Superoxides/metabolism, Tyrosine/pharmacology, Xanthine Oxidase/metabolism
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