Hypoxia induces permeability in brain microvessel endothelial cells via VEGF and NO.
In this study, an in vitro model of the blood-brain barrier, consisting of porcine brain-derived microvascular endothelial cells (BMEC), was used to evaluate the mechanism of hypoxia-induced hyperpermeability. We show that hypoxia-induced permeability in BMEC was completely abolished by a neutralizing antibody to vascular endothelial growth factor (VEGF). In contrast, under normoxic conditions, addition of VEGF up to 100 ng/ml did not alter monolayer barrier function. Treatment with either hypoxia or VEGF under normoxic conditions induced a twofold increase in VEGF binding sites and VEGF receptor 1 (Flt-1) mRNA expression in BMEC. Hypoxia-induced permeability also was prevented by the nitric oxide (NO) synthase inhibitor NG-monomethyl-L-arginine, suggesting that NO is involved in hypoxia-induced permeability changes, which was confirmed by measurements of the cGMP level. During normoxia, treatment with VEGF (5 ng/ml) increased permeability as well as cGMP content in the presence of several antioxidants. These results suggest that hypoxia-induced permeability in vitro is mediated by the VEGF/VEGF receptor system in an autocrine manner and is essentially dependent on reducing conditions stabilizing the second messenger NO as the mediator of changes in barrier function of BMEC.
Fischer
S
S
Department of Anesthesiology and Intensive Care, Max Planck Institute for Physiological and Clinical Research, 61231 Bad Nauheim, Germany. sfischer@kerckhoff.mpg.de
Clauss
M
M
Wiesnet
M
M
Renz
D
D
Schaper
W
W
Karliczek
G F
GF
D000818:Animals; D002196:Capillaries; D015687:Cell Hypoxia; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D016228:Endothelial Growth Factors / Q000276:immunology / Q000494:pharmacology / Q000502:physiology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D007444:Inulin / Q000494:pharmacology; D008222:Lymphokines / Q000276:immunology / Q000494:pharmacology / Q000502:physiology*; D008954:Models, Biological; D009569:Nitric Oxide / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D013552:Swine; D008063:Thioctic Acid / Q000494:pharmacology; D014158:Transcription, Genetic; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D042442:Vascular Endothelial Growth Factors; D019323:omega-N-Methylarginine / Q000494:pharmacology
D016228:Endothelial Growth Factors; D008222:Lymphokines; D011518:Proto-Oncogene Proteins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D009599:Nitroprusside; D019323:omega-N-Methylarginine; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D008063:Thioctic Acid; D007444:Inulin; D020794:Receptor Protein-Tyrosine Kinases; D040281:Vascular Endothelial Growth Factor Receptor-1; D006152:Cyclic GMP