Inhibition of superoxide generation from fMLP-stimulated leukocytes by high concentrations of nitric oxide or peroxynitrite: characterization by electron spin resonance spectroscopy.
This present study examined the effects of high concentrations of nitric oxide (NO*) and peroxynitrite (ONOO-) on superoxide (O2*-) production from formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated polymorphonuclear leukocytes (PMNs) by using electron spin resonance (ESR) and spin trapping with 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO). We demonstrated that ONOO- (100 microM) decreased the ESR signal of DEPMPO-OOH from fMLP-activated PMNs, indicating the inhibition of O2*- generation, while it enhanced the signal of DEPMPO-OH. Inhibition of the respiratory burst was also observed when PMNs were pre-exposed to high concentrations of NO* (100 microM), generated by the NO* donor NOR-1, 30 min prior to stimulation with fMLP. NOR-1 inhibited O2*- generation more effectively under conditions in which ONOO-was formed concurrently. The ability of high concentrations of either ONOO- or NO* to inhibit O2*-generation from fMLP-stimulated PMNs is relevant to pathophysiological conditions, such as severe inflammation, in which NO* or ONOO- production can be significantly elevated.
Lee
Masaichi-Chang-il
MC
Department of Pharmacology and ESR Laboratories, Kanagawa Dental College, Kanagawa, Yokosuka, Japan. ieeman@kdcnet.ac.jp
Shoji
Hirofumi
H
Komatsu
Tomoko
T
Yoshino
Fumihiko
F
Ohmori
Yoichi
Y
Zweier
Jay L
JL
D003497:Cyclic N-Oxides / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D007249:Inflammation; D007962:Leukocytes / Q000187:drug effects / Q000473:pathology*; D008280:Magnetics; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000494:pharmacology*; D013113:Spin Labels; D019097:Spin Trapping; D013481:Superoxides; D013997:Time Factors
D003497:Cyclic N-Oxides; D013113:Spin Labels; D013481:Superoxides; D030421:Peroxynitrous Acid; C098505:5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide; D009569:Nitric Oxide; D009240:N-Formylmethionine Leucyl-Phenylalanine; D010100:Oxygen