Generation of superoxide anion by brain endothelial cell xanthine oxidase

Bovine brain endothelial cells (EC) that were isolated and propagated in pure culture had increased ( 20-fold) levels of xanthine oxidase and xanthine dehydrogenase activity compared to whole brain homogenate. Brain EC also released superoxide anion (O) in to the extracellular medium. Treatment of EC with tungsten decreased (P < 0.05), both XO activity and O release. XO appears to be highly concentrated in cerebral vascular endothelium and may be an important source o; O.