Relationship between catalase activity and uptake of elemental mercury by rat brain

Uptake of mercury by brain after intravenous injection of elemental mercury was investigated in the rat. Catalase activity was inhibited by aminotriazole either by intraperitoneal injections affecting catalase in most tissues of the animal or by intraventricular injections affecting catalase in the brain selectively. Uptake of elemental mercury by rat brain was not influenced by intraperitoneal administration of aminotriazole resulting in 50% inhibition of brain catalase. However, when the inhibitor was injected intraventricularly in concentrations to give a 50% inhibition of brain catalase, it was shown that the mercury uptake by the brain was significantly decreased. In the latter case when only brain catalase was inhibited and the supply of elemental mercury to brain was maintained, mercury uptake by brain was proportional to the activity of catalase in brain tissue and to the injected amount of elemental mercury. Contrary to the intraventricular injection of aminotriazole, in animals receiving aminotriazole intraperitoneally prior to elemental mercury injection, we suggest that the lower activity of brain catalase is compensated by an increased supply of elemental mercury caused by the generally lower oxidation rate in the animal. This view is supported by the finding that mercury uptake by liver increased due to aminotriazole intraperitoneally although activity of catalase was depressed.