NOS2 and serum lipopolysaccharide activity: In addition, ketamine has been shown to attenuate symptoms of endotoxemia in a lipopolysaccharide (LPS)-induced rat model of of sepsis, by reducing NF-kappa B activity and TNF-alpha production [11], and decreasing the expression of inducible nitric oxide synthase (iNOS) [12], which has been implicated in endotoxin-induced tissue injury.