Nitric oxide (.NO) release, oxygen uptake and hydrogen peroxide (H2O2) production elicited by increasing phorbol 12-myristate 13-acetate (PMA) concentrations were measured in human neutrophils. Half-maximal activities were sequentially elicited at about 0.0001-0.001 micrograms PMA/ml (.NO) and 0.001-0.01 micrograms PMA/ml (H2O2). At saturated PMA concentrations, .NO production, oxygen uptake and H2O2 release were 0.56 +/- 0.04, 3.32 +/- 0.52 and 1.19 +/- 0.17 nmol.min-1.10(6) cells-1. .NO production accounts for about 30% of the total oxygen uptake. Luminol-dependent chemiluminescence, reported to detect NO reactions in other inflammatory cells, was also half-maximally activated at about 0.001-0.01 micrograms PMA/ml. Preincubation with NG-monomethyl-L-arginine (L-NMMA) decreased O2 uptake and .NO release but increased H2O2 production, while superoxide dismutase (SOD) increased .NO detection by 30%. Chemiluminescence was also reduced by preincubation with L-NMMA and/or SOD. The results indicate that .NO release is part of the integrated response of stimulated human neutrophils and that, in these cells, kinetics of .NO and O2.- release favour the formation of other oxidants like peroxynitrite.