Os radicais livres derivados do oxigênio na isquemia cerebral transitória

This experimental study has the objective of stndying the lesions that the oxygen-derived free radicals might produce in the brain, in the presence of both total and transient cerebral ischemia, and also to testing the effects of scavengers through the reduction of the Nitro Blue Tetrazolium (NBT) optic colourant. Thirty-two rabbits were distributed in four gnntps, each group consisting of eight animals. Group I wasnt subjected to cerebral ischemia. Groups II, III and IV rabbits were subjected to transient cerebral ischemia under controlled hipotension, during sixty minutes and followed by thirty minutes of reperfusion. In groups III and IV, N-acetyl-cysteine and Deferoxamine were respectively used before reperfusion. It was observed in group II, after using NBT, an abundant release of oxygen derived free radicals with hystopathologic evaluation showing tissuee damage. The importance of iron as the catalyst of the reactions that generate free inorganic radicals and of the reactions which are able to create free organic radicals from products of the arachdonic acid metabolism are also emphasysed. Finally, comments are made of the free radical antioxidant effect, wich had a protective effect ou cerebral tissue, preventing hystopathologic lesions. These results show the importance of prophylatic usage of these scavengers in transient cerebral ischemia.