[The effect of oxidative stress on brain nitric oxide synthase activity in vivo and in vitro]

Within 8 days of a 10-min cardiac arrest, accumulation of material reacting with 2-thiobarbituric acid was revealed in the hippocampus (74%) and cerebellum (47%) of male Wistar rats. Oxidative stress was accompanied by a twofold decrease of the nitric oxide synthase activity in the brain tissue. In vitro experiments showed a dose-dependent decrease of nitric oxide synthase activity in the brain homogenates as a result of the oxidative stress induced by hydrogen peroxide or sodium hypochlorite. The findings suggest that the oxidative stress may decrease nitric oxide synthase activity as a result of direct effects of the active oxygen on the enzyme.