Nitrosative capacity of macrophages is dependent on nitric-oxide synthase induction signals

Nitrosative stress can occur when reactive nitric oxide (NO) species compro mise the function of biomolecules via formation of NO adducts on critical a mine and thiol residues. The capacity of inducible nitric-oxide synthase (i NOS) to generate nitrosative stress was investigated in the murine macropha ge line ANA-1. Sequential activation with the cytokines IFN-gamma and eithe r tumor necrosis factor-alpha or interleukin-1 beta resulted in the inducti on of iNOS and production of nitrite (20 nM/min) but failed to elicit nitro sation of extracellular 2,3-diaminonapthalene. Stimulation with IFN-gamma a nd bacterial lipopolysaccharide increased the relative level of iNOS protei n and nitrite production of ANA-1 cells S-fold; however, a substantial leve l of NO in the media was also observed, and nitrosation of 2,3-diaminonapth alene was increased greater than 30-fold. Selective scavenger compounds sug gested that the salient nitrosating mechanism was the NO/O-2 reaction leadi ng to N2O3 formation. These data mimicked the pattern observed with a 5 mu M concentration of the synthetic NO donor (Z)-1-[N-ammoniopropyl) -N-(n-pro pyl) aminoldiazen-1-ium- 1,2-diolate (PAPA/NO), The NO profiles derived fro m iNOS can be distinct and depend on the inductive signal cascades. The div erse consequences of NO production in macrophages may reside in the cellula r mechanisms that control the ability of iNOS to form N2O3 and elicit nitro sative stress.