Free radical-induced endothelial membrane dysfunction at the site of blood-brain barrier: relationship between lipid peroxidation, Na,K-ATPase activity, and 51Cr release.
Na,K-ATPase activity, membrane lipid peroxidation (TBARM), and membrane 'leakiness' for small molecules were examined in rat cerebromicrovascular endothelial cells (RCEC) following exposure to hydrogen peroxide and xanthine/xanthine oxidase. Whereas short-term (15-30 min) exposure to either oxidant decreased ouabain-sensitive 86Rb uptake and increased TBARM in a concentration-dependent fashion, significant release of 51Cr (30-40%) from cells was observed only after one hour exposure to the oxidants. By comparison, much longer exposure times (i.e., 4 hours) were needed to induce significant lactate dehydrogenase release from oxidant-treated cells. The oxidant-evoked decrease in Na,K-ATPase activity and increases in TBARM and RCEC 'permeability' were abolished in the presence of the steroid antioxidants U-74500A and U-74389G (5-20 microM). Reduced glutathione (4 mM) partially attenuated oxidant-induced changes, whereas ascorbic acid (2 mM) and the disulfide bond-protecting agent, dithiothreitol (1 mM), were ineffective. These results suggest that the oxidant-induced loss of Na,K-ATPase activity in RCEC results primarily from changes in membrane lipids, and implicate both the inhibition of Na,K-ATPase and membrane lipid peroxidation in the mechanism responsible for the delayed free radical-induced increase in RCEC membrane 'permeability'.
Stanimirovic
D B
DB
Institute for Biological Sciences, National Research Council of Canada, Ottawa. Danica@biologym54.lan.nrc.ca
Wong
J
J
Ball
R
R
Durkin
J P
JP
D000818:Animals; D001812:Blood-Brain Barrier; D001921:Brain / Q000098:blood supply; D002462:Cell Membrane / Q000378:metabolism; D002860:Chromium Radioisotopes / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D005609:Free Radicals; D005978:Glutathione / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects*; D010042:Ouabain / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012414:Rubidium Radioisotopes / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D019820:Xanthine; D014969:Xanthine Oxidase / Q000378:metabolism; D014970:Xanthines / Q000378:metabolism
D002860:Chromium Radioisotopes; D005609:Free Radicals; D016877:Oxidants; D012414:Rubidium Radioisotopes; D014970:Xanthines; D019820:Xanthine; D010042:Ouabain; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D014969:Xanthine Oxidase; D000254:Sodium-Potassium-Exchanging ATPase; D005978:Glutathione