STUDIES ON NITRIC-OXIDE FREE-RADICALS GENERATED FROM POLYMORPHONUCLEAR LEUKOCYTES (PMN) STIMULATED BY PHORBOL-MYRISTATE ACETATE (PMA)

The interaction of NO and O-2(-) free radicals generated from PMA (pho rbol 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-2(-) by DMPO and addition of N-G- monomethyl-arginine (NGMA) would significantly increase the trapped O- 2(-) by DMPO. It was proved that the formation of ONOO- by the reactio n of NO and O-2(-) was the main reason for the decrease of trapped O-2 (-) in the experiment with xanthine/xanthine oxidase and irradiation o f riboflavin systems. The yield of NO during this process was calculat ed. The generation dynamic of NO was studied by a luminol-dependent ch emiluminescence technique and it was found that after stimulation of P MN by PMA, there would be an immediate, significant chemiluminescence, which came mainly from the active oxygen free radicals generated by P MN. If L-arginine was added to this system, the chemiluminescence woul d increase about 100-fold, but NGMA inhibited the increase of the chem iluminescence. Ten minutes after addition of L-arginine, this increase did not change, the chemiluminescence peak decreased gradually, but t he half life increased. The ESR and chemiluminescence properties of NO and ONOO- synthesized were also studied in model systems. (C) 1996 Ac ademic Press Limited