TY - JOUR
T1 - Superoxide and peroxynitrite generation from inducible nitric oxide synthase in macrophages
AU - Xia, Yong
AU - Zweier, Jay L.
PY - 1997/6/24
Y1 - 1997/6/24
N2 - Superoxide (O2/-·) and nitric oxide (NO) act to kill invading microbes in phagocytes. In macrophages NO is synthesized by inducible nitric oxide synthase (iNOS, NOS 2) from L-arginine (L-Arg) and oxygen; however, O2/-· was thought to be produced mainly by NADPH oxidase. Electron paramagnetic resonance (EPR) spin trapping experiments performed in murine macrophages demonstrate a novel pathway of O2/-· generation. It was observed that depletion of cytosolic L-Arg triggers O2/-· generation from iNOS. This iNOS-mediated O2/-· generation was blocked by the NOS inhibitor N-nitro-L-arginine methyl ester or by L-Arg, but not by the noninhibitory enantiomer N-nitro-D-arginine methyl ester. In L-Arg-depleted macrophages iNOS generates both O2/-· and NO that interact to form the potent oxidant peroxynitrite (ONOO-), which was detected by luminol luminescence and whose formation was blocked by superoxide dismutase, urate, or L-Arg. This iNOS- derived ONOO- resulted in nitrotyrosine formation, and this was inhibited by iNOS blockade. iNOS-mediated O2/-· and ONOO- increased the antibacterial activity of macrophages. Thus, with reduced L-Arg availability iNOS produces O2/-· and ONOO- that modulate macrophage function. Due to the existence of L-Arg depletion in inflammation, iNOS-mediated O2/-· and ONOO- may occur and contribute to cytostatic/cytotoxic actions of macrophages.
AB - Superoxide (O2/-·) and nitric oxide (NO) act to kill invading microbes in phagocytes. In macrophages NO is synthesized by inducible nitric oxide synthase (iNOS, NOS 2) from L-arginine (L-Arg) and oxygen; however, O2/-· was thought to be produced mainly by NADPH oxidase. Electron paramagnetic resonance (EPR) spin trapping experiments performed in murine macrophages demonstrate a novel pathway of O2/-· generation. It was observed that depletion of cytosolic L-Arg triggers O2/-· generation from iNOS. This iNOS-mediated O2/-· generation was blocked by the NOS inhibitor N-nitro-L-arginine methyl ester or by L-Arg, but not by the noninhibitory enantiomer N-nitro-D-arginine methyl ester. In L-Arg-depleted macrophages iNOS generates both O2/-· and NO that interact to form the potent oxidant peroxynitrite (ONOO-), which was detected by luminol luminescence and whose formation was blocked by superoxide dismutase, urate, or L-Arg. This iNOS- derived ONOO- resulted in nitrotyrosine formation, and this was inhibited by iNOS blockade. iNOS-mediated O2/-· and ONOO- increased the antibacterial activity of macrophages. Thus, with reduced L-Arg availability iNOS produces O2/-· and ONOO- that modulate macrophage function. Due to the existence of L-Arg depletion in inflammation, iNOS-mediated O2/-· and ONOO- may occur and contribute to cytostatic/cytotoxic actions of macrophages.
KW - Cytotoxicity
KW - Electron paramagnetic resonance
KW - L-arginine
KW - NADPH oxidase
KW - Nitrotyrosine
UR - http://www.scopus.com/inward/record.url?scp=0031002421&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0031002421&partnerID=8YFLogxK
U2 - 10.1073/pnas.94.13.6954
DO - 10.1073/pnas.94.13.6954
M3 - Article
C2 - 9192673
AN - SCOPUS:0031002421
SN - 0027-8424
VL - 94
SP - 6954
EP - 6958
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 13
ER -