title: Nitric oxide/cGMP protects endothelial cells from hypoxia-mediated leakiness.
abstract: Leakiness of the endothelial bed is attributed to the over-perfusion of the pulmonary bed, which leads to high altitude pulmonary edema (HAPE). Inhalation of nitric oxide has been successfully employed to treat HAPE patients. We hypothesize that nitric oxide intervenes in the permeability of the pulmonary macrovascular endothelial bed to rectify the leaky bed under hypoxia. Our present work explores the underlying mechanism of 'hypoxia-mediated' endothelial malfunction by using human umbilical cord-derived immortalized endothelial cells, ECV-304, and bovine pulmonary artery primary endothelial cells. The leakiness of the endothelial monolayer was increased by two-fold under hypoxia in comparison to cells under normoxia, while optical tweezers-based tethering assays reported a higher membrane tension of endothelial cells under hypoxia. Phalloidin staining demonstrated depolymerization of F-actin stress fibers and highly polarized F-actin patterns in endothelial cells under hypoxia. Nitric oxide, 8-Br-cGMP and sildenafil citrate (phosphodiesterase type 5 inhibitor) led to recovery from hypoxia-induced leakiness of the endothelial monolayers. Results of the present study also suggest that 'hypoxia-induced' cytoskeletal rearrangements and membrane leakiness are associated with the low nitric oxide availability under hypoxia. We conclude that nitric oxide-based recovery of hypoxia-induced leakiness of endothelial cells is a cyclic guanosine monophosphate (cGMP)-dependent phenomenon.
authors.affiliation: Vascular Biology Laboratory, AU-KBC Research Centre, MIT Campus, Anna University, Chennai 600 044, Tamil Nadu, India.
authors.forename: Gopi Krishna
authors.initials: GK
authors.lastname: Kolluru
authors.forename: K P
authors.initials: KP
authors.lastname: Tamilarasan
authors.forename: Arun Stephen
authors.initials: AS
authors.lastname: Rajkumar
authors.forename: S
authors.initials: S
authors.lastname: Geetha Priya
authors.forename: Megha
authors.initials: M
authors.lastname: Rajaram
authors.forename: Niyas K
authors.initials: NK
authors.lastname: Saleem
authors.forename: Syamantak
authors.initials: S
authors.lastname: Majumder
authors.forename: B M
authors.initials: BM
authors.lastname: Jaffar Ali
authors.forename: G
authors.initials: G
authors.lastname: Illavazagan
authors.forename: Suvro
authors.initials: S
authors.lastname: Chatterjee
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002199:Capillary Permeability / Q000502:physiology; D002417:Cattle; D015687:Cell Hypoxia; D002460:Cell Line; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D009569:Nitric Oxide / Q000378:metabolism*
chemical_list: D000199:Actins; D009569:Nitric Oxide; D006152:Cyclic GMP