['To evaluate the effects of ketamine on the activity and protein expression of inducible nitric oxide synthase (iNOS) induced by lipopolysaccharide (LPS) in rat alveolar macrophages.', 'Pulmonary alveolar macrophages isolated from Wistar-Kyoto rats were used. After incubation of macrophages with ketamine (1, 10, or 100 microM) and LPS (1 microgram.ml-1) for 24 hr, the cell-free medium was removed for measuring the nitrite and tumour necrosis factor-alpha (TNF-alpha) levels by Griess reaction and ELISA kit, respectively. The harvested macrophages were also used to determine the activity of iNOS by using the conversion of [3H]-L-arginine to [3H]-L-citrulline method. In addition, the protein expression of iNOS was detected by Western blot analysis.', 'In rat alveolar macrophages, (i) ketamine (1 to 100 microM) caused a dose-dependent suppression of the production of nitrite and TNF-alpha induced by LPS and (ii) ketamine (100 microM) inhibited the activity (46.5 +/- 4.8%, P < 0.05) and protein expression (35 +/- 11%, P < 0.05) of iNOS in response to LPS.'] Does ketamine inhibit nitric oxide synthase in lipopolysaccharide-treated rat alveolar macrophages?