title: Direct ANP inhibition of hypoxia-induced inflammatory pathways in pulmonary microvascular and macrovascular endothelial monolayers.
abstract: Atrial natriuretic peptide (ANP) has been shown to reduce hypoxia-induced pulmonary vascular leak in vivo, but no explanation of a mechanism has been offered other than its vasodilatory and natriuretic actions. Recently, data have shown that ANP can protect endothelial barrier functions in TNF-alpha-stimulated human umbilical vein endothelial cells. Therefore, we hypothesized that ANP actions would inhibit pulmonary vascular leak by inhibition of TNF-alpha secretion and F-actin formation. Bovine pulmonary microvascular (MVEC) and macrovascular endothelial cell (LEC) monolayers were stimulated with hypoxia, TNF-alpha, or bacterial endotoxin (LPS) in the presence or absence of ANP, and albumin flux, NF-kappa B activation, TNF-alpha secretion, p38 mitogen-activated protein kinase (MAPK), and F-actin (stress fiber) formation were assessed. In Transwell cultures, ANP reduced hypoxia-induced permeability in MVEC and TNF-alpha-induced permeability in MVEC and LEC. ANP inhibited hypoxia and LPS increased NF-kappa B activation and TNF-alpha synthesis in MVEC and LEC. Hypoxia decreased activation of p38 MAPK in MVEC but increased activation of p38 MAPK and stress fiber formation in LEC; TNF-alpha had the opposite effect. ANP inhibited an activation of p38 MAPK in MVEC or LEC. These data indicate that in endothelial cell monolayers, hypoxia activates a signal cascade analogous to that initiated by inflammatory agents, and ANP has a direct cytoprotective effect on the pulmonary endothelium other than its vasodilatory and natriuretic properties. Furthermore, our data show that MVEC and LEC respond differently to hypoxia, TNF-alpha-stimulation, and ANP treatment.
authors.affiliation: Dept. of Biomedical Sciences, College of Veterinary and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA. Davidcirwin@earthlink.net
authors.forename: D C
authors.initials: DC
authors.lastname: Irwin
authors.forename: M C
authors.initials: MC
authors.lastname: Tissot van Patot
authors.forename: A
authors.initials: A
authors.lastname: Tucker
authors.forename: R
authors.initials: R
authors.lastname: Bowen
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002199:Capillary Permeability / Q000187:drug effects / Q000276:immunology; D002417:Cattle; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D000860:Hypoxia / Q000188:drug therapy* / Q000276:immunology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008168:Lung / Q000098:blood supply / Q000276:immunology*; D008833:Microcirculation / Q000276:immunology; D016328:NF-kappa B / Q000378:metabolism; D011108:Polymers / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D022502:Stress Fibers / Q000187:drug effects / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000199:Actins; D008070:Lipopolysaccharides; D016328:NF-kappa B; D011108:Polymers; D014409:Tumor Necrosis Factor-alpha; D009320:Atrial Natriuretic Factor; D048051:p38 Mitogen-Activated Protein Kinases