Fig. 2. Dose response of aminoguanidine reversal of lipopolysaccharide plus interferon γ–induced decrease of cell viability. Rat NR8383 macrophages were incubated with or without 100 ng/ml lipopolysaccharide plus 50 U/ml interferon γ in the presence or absence of various concentrations of aminoguanidine. Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results are mean ± SD (n = 28). *  P < 0.05 compared with the corresponding cells exposed to lipopolysaccharide plus interferon γ only.