HYPOXIA AND REOXYGENATION OF BRAIN ENDOTHELIAL-CELLS IN-VITRO - A COMPARISON OF BIOCHEMICAL AND MORPHOLOGICAL RESPONSE

Reactive oxygen species are thought to be important for a variety of p athological processes in the brain. Endothelial cells have been propos ed as both a significant source of oxidants and targets of oxidative d amage. Therefore, lipid peroxidation (LPO) was investigated and compar ed to biochemical and morphological alterations in cultured pig brain capillary endothelial cells after hypoxia (120 min. 95% N-2/5% CO2) an d reoxygenation (30 min. 95% O-2/5% CO2). The content of thiobarbituri c acid reactive substances (TBARS) representing radical-induced LPO wa s 2.50 +/- 0.46 after hypoxia and 5.92 +/- 0.54 nmol/mg protein after reoxygenation (p<0.05 each, vs, normoxic control 1.79 +/- 0.21). Durin g hypoxia, ATP content decreased to 7.9 +/- 1.6 nmol/mg protein; lacta te dehydrogenase activity in the incubation solution increased to 0.17 +/- 0.03 U/mg protein; (p<0.05 vs. control 15.7 +/- 3.1 and 0.09 +/- 0.02, respectively). After hypoxia, morphological changes in lysosomes , multivesicular bodies and vacuoles were observed in contrast to norm oxic cells. During reoxygenation, the ATP values were normalized; elec tron micrographs showed increasing amounts of lysosomes, multivesicula r bodies, vacuoles, blebs and lipofuscin granula and lyzed cells. Comp aring the biochemical and morphological observations, a sequence of di sturbances occurred, in which energy depletion was accompanied and fol lowed, respectively, by membrane destruction, cellular disintegration and an increase in LPO products. These results support the assumption that the damage of brain endothelial cells caused by hypoxia and reoxy genation is accompanied by peroxidation of membrane lipids.