AbstractThe interaction of NO and O−2free radicals generated from PMA (phorbol myristate acetate)‐stimulated PMN (polymorphonuclear leukocytes) was studied by a nitroxide spin trap, DMPO (5,5‐dimethyl‐1‐pyrroline‐1‐oxide). It was found that addition of L‐arginine to the system would significantly decrease the trapped O−2by DMPO and addition of NG‐monomethyl‐arginine (NGMA) would significantly increase the trapped O−2by DMPO. It was proved that the formation of ONOO−by the reaction of NO and O−2was the main reason for the decrease of trapped O−2in the experiment with xanthine/xanthine oxidase and irradiation of riboflavin systems. The yield of NO during this process was calculated. The generation dynamic of NO was studied by a luminol‐dependent chemiluminescence technique and it was found that after stimulation of PMN by PMA, there would be an immediate, significant chemi‐luminescence, which came mainly from the active oxygen free radicals generated by PMN. If L‐arginine was added to this system, the chemiluminescence would increase about 100‐fold, but NGMA inhibited the increase of the chemiluminescence. Ten minutes after addition of L‐arginine, this increase did not change, the chemiluminescence peak decreased gradually, but the half life increased. The ESR and chemiluminescence properties of NO and ONOO−synth
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