SIMULATED ISCHEMIA-REPERFUSION CONDITIONS INCREASE XANTHINE DEHYDROGENASE AND OXIDASE ACTIVITIES IN RAT-BRAIN SLICES

Xanthine dehydrogenase and oxidase activities increased by 87% in rat brain slices after 30 min in vitro ischaemia. A further 41% increase w as induced by 30 min simulated reperfusion of ischaemic slices. No con version from the dehydrogenase to the oxidase activity was observed. T he increment of enzyme activity was not due to neosynthesis of the enz yme, since it was not affected by the addition of cycloheximide during the ischaemic incubation. The increased oxygen-dependent form of the enzyme could aggravate the ischaemic brain injury by free radicals pro duction, in particular after reperfusion. (C) 1998 Published by Elsevi er Science Ltd. All rights reserved.