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Systemic and Pulmonary Microvascular Endothelial Cells (EC) Respond Differently to Hypoxia
Author(s) -
Choudhary Gaurav,
Jackson Heather,
Koutab Nicholas,
Harrington Elizabeth O
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a751-a
Subject(s) - hypoxia (environmental) , enos , nitric oxide , protein kinase b , chemistry , vasodilation , hypoxic pulmonary vasoconstriction , endocrinology , vascular permeability , medicine , endothelium , vasoconstriction , pharmacology , phosphorylation , nitric oxide synthase , biology , biochemistry , oxygen , organic chemistry
Hypoxia causes vasoconstriction in the pulmonary circulation and vasodilation in the systemic circulation. The heterogeneous response of microvascular EC to hypoxia in the pulmonary and systemic vasculature is poorly understood. We evaluated the effects of hypoxia on microvascular monolayer permeability and explored underlying signaling mechanisms. Microvascular EC isolated from rat lungs (RL) and hearts (RH) were exposed to hypoxia (H) or normoxia (N). Changes in monolayer permeability were assessed by measuring HRP diffusion through monolayers cultured in transwell chambers and by monitoring the resistance across monolayers. Hypoxia increased HRP diffusion in RL (0.16ng/ml±0.02 vs. 0.26ng/ml±0.03, p<0.05), but not in RH (0.31ng/ml±0.05 vs. 0.28ng/ml±0.02, p=NS). Similarly, resistance across RL monolayers decreased over 24h hypoxia exposure. To assay potential signaling pathways involved, we monitored nitric oxide (NO) production and protein and activity levels of eNOS and Akt. Flow cytometric analysis of DAF‐FM loaded EC showed increased NO in 24h hypoxic RL (N: 24.4±2 vs. H: 43.6±8) and RH (N: 4.0±0.1 vs. H: 4.7±0.2). The total protein amounts of eNOS and Akt were similar in hypoxic and normoxic RL and RH. No significant changes in phosphorylated eNOS S 1177 were noted in hypoxic and normoxic RL vs. RH, yet hypoxia decreased phosphorylated Akt S 473 in RH, but not RL, relative to normoxia (0.74±0.04). Thus, hypoxia differentially affects monolayer permeability and NO production in microvascular EC isolated from pulmonary and systemic vasculature. Funded by: HL67795, VA Merit Review.