Propofol, widely used as a sedative agent, is known to exert antioxidant and anti-inflammatory effects in vitro. We studied the effects of propofol on hemodynamics and the function of several organs in conscious rats with endotoxemia. Intravenous injection of rats with endotoxin (lipopolysaccharide) caused hypotension, vascular hyporeactivity and tachycardia as well as significant lung, liver and kidney damage. Hepatocellular damage caused by lipopolysaccharide for 6 h was significantly attenuated in the lipopolysaccharide+propofol group. Aortic superoxide anion (O(2)(radical)(-)) production, but not plasma nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) level, was also suppressed by propofol in lipopolysaccharide-injected rats. Light microscopy showed that propofol attenuated the marked infiltration of neutrophils in liver tissues from lipopolysaccharide-injected rats. Moreover, the survival rate of the lipopolysaccharide+propofol group at 16 h was significantly increased when compared with that of the lipopolysaccharide group (53% vs. 12%). These results suggest that inhibition of aortic O(2)(radical)(-) production and amelioration of liver dysfunction contribute to the beneficial effect of propofol in conscious rats with endotoxic shock.