BACKGROUND: It is a well known phenomenon that alveolar and peritoneal macrophages exposed to bacterial lipopolysaccharide (LPS) induce a large output of nitric oxide (NO) and an inducible nitric oxide synthase (iNOS) m-RNA expression. The author elucidate the effects on NO production and iNOS m-RNA expression of various anesthetics, inhalational (halothane, enflurane, sevoflurane) and intravenous (ketamine, propofol), on endotoxemic rats. METHODS: To examine the production of NO in peritoneal macrophages, NO concentrations were measured from the rats following 2 hours exposure to LPS and 2 hours administration of various anesthetics, respectively. Culture supernatants were collected 24 hours after exposure to LPS and anesthetics and assayed by ELISA (Enzyme Linked Immunosorbent Assay) for production of NO. iNOS m-RNA expression was measured using PCR (Polymerase Chain Reaction) techniques and autoradiography. RESULTS: In the control group, the NO concentration was measured at 120 minutes after infusion of LPS to rats, and showed 12+/-4 micrometer. After insufullation of anesthetics to experimental animals, NO concentration increased in the halothane, enflurane, sevoflurane, propofol, and ketamine groups, 132+/-27 (P< 0.05), 49+/-19 (P< 0.05), 23+/-14 (P< 0.05), 37+/-11 (P< 0.05), and 17+/-2 micrometer respectively. The size and brightness of the iNOS m-RNA bands were large in halothane, enflurane, sevoflurane, propofol and ketamine, in order. CONCLUSIONS: Intravenous anesthetics showed more stability than inhalation anesthetics with regand to production of NO and iNOS m-RNA expression in sepsis on rats. The mechanism is not clear, but it is related to the strong stimulating effect to the airway tract in from inhalational anesthetics.