Nitric oxide protects blood-brain barrier in vitro from hypoxia/reoxygenation-mediated injury

A cell culture model of blood-brain barrier (BBB, coculture of rat brain endothelial cells with rat astrocytes) was used to investigate the effect of nitric oxide ((NO)-N-.) on the damage of the BBB induced by hypoxia/reoxygenation (H/R), Permeability coefficient of fluorescein across the endothelium was used as a marker of BBB tightness. The permeability coefficient increased 5.2 times after H/R indicating strong disruption of the BBB, The presence of the (NO)-N-. donor S-nitroso-N-acetylpenicillamine (SNAP, 30 mu M), authentic (NO)-N-. (6 mu M) or superoxide dismutase (50 units/ml) during H/R attenuated H/R-induced increase in permeability. 30 mu M SNAP or 6 mu M (NO)-N-. did not influence the function of BBB during normoxia, however, severe disruption was observed using 150 mu M of SNAP and more than 24 mu M of (NO)-N-.. After H/R of endothelial cells, the content of malondialdehyde (MDA) increased 2.3 times indicating radical-induced peroxidation of membrane lipids, 30 mu M SNAP or 6 mu M authentic (NO)-N-. completely prevented MDA formation, The results show that (NO)-N-. may effectively scavenge reactive oxygen species formed during H/R of brain capillary endothelial cells, affording protection of BBB at the molecular and functional level. (C) 1998 Federation of European Biochemical Societies.