Macrophage synthesis of nitrite, nitrate, and N-nitrosamines: precursors and role of the respiratory burst.
The macrophage cell line RAW 264.7 when activated with Escherichia coli lipopolysaccharide and interferon-gamma synthesized nitrite (NO3-) and nitrate (NO3-). Medium change after the activation showed that L-arginine was the only amino acid essential for this synthesis. D-Arginine would not substitute for L-arginine. Other analogues that could replace L-arginine were L-homoarginine, L-arginine methyl ester, L-arginamide, and the peptide L-arginyl-L-aspartate. L-Argininic acid, L-agmatine, L-ornithine, urea, L-citrulline, and ammonia were among the nonprecursors, while L-canavanine inhibited this L-arginine-derived NO2-/NO3- synthesis. When morpholine was added to the culture medium of the activated RAW 264.7 macrophages, N-nitrosation took place, generating N-nitrosomorpholine. GC/MS experiments using L-[guanido-15N2]arginine established that the NO2-/NO3- and the nitrosyl group of N-nitrosomorpholine were derived exclusively from one or both of the terminal guanido nitrogens of arginine. Chromatographic analysis showed that the other product of the L-arginine synthesis of NO2-/NO3- was L-citrulline. The role of the respiratory burst in NO2-/NO3- synthesis was examined using the macrophage cell lines J774.16 and J774 C3C. Both cell lines synthesized similar amounts of NO2-/NO3-. However, J774 C3C cells do not produce superoxide and hence do not exhibit the respiratory burst. Additional experiments also ruled out the involvement of the respiratory burst in NO2-/NO3- synthesis.
Iyengar
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R
Stuehr
D J
DJ
Marletta
M A
MA
D001120:Arginine / Q000378:metabolism; D002956:Citrulline / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008262:Macrophage Activation; D008264:Macrophages / Q000502:physiology*; D009025:Morpholines / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D009602:Nitrosamines / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
D009025:Morpholines; D009566:Nitrates; D009573:Nitrites; D009602:Nitrosamines; D013481:Superoxides; D002956:Citrulline; C037574:morpholine; D001120:Arginine; D006861:Hydrogen Peroxide