AIM To study the effects of aminoguanidine(AG) and two L-arginine analogues Nω-nitro-L-arginine methyl ester (L-NAME) and Nω-nitro-L-arginine (L-NNA) on nitric oxide (NO) productioninduced by cytokines (TNF-α, IL-11β, and IFN-γ)and bacterial lipopolysaccharide (LPS) mixture(CM) in the cultured rat hepatocytes, andexamine their mechanisms action.METHODS Rat hepatocytes were incubatedwith AG, L-NAME, L-NNA, Actinomycin D (ActD)and dexamethasene in a medium containing CM(LPS plus TNF-α, IL-1β, and IFN-γ) for 24 h. NOproduction in the cultured supernatant wasmeasured with the Griese reaction. IntracellularcGMP level was detected with radioimmunoasey.RESULTS NO production was markedlyblocked by AG and L-NAME in a dose-dependentmanner under inflammatory stimuli conditiontriggered by CM in vitro. The rate of themaximum inhibitory effects of L-NAME (38.9%)was less potent than that obtained with AG(53.7%, P