title: VEGF-induced blood flow increase causes vascular hyper-permeability in vivo.
abstract: VEGF is known to cause vascular leak, its detailed mechanisms in vivo remain unclear. Here, we investigated the mechanisms underlying VEGF-induced vascular hyper-permeability focusing on two major regulators of vascular permeability: blood flow and endothelial barrier function. Administration of VEGF caused vascular hyper-permeability and tissue swelling in mouse ears, which were abolished by VEGF receptor-2 blockade. Intravital imaging showed that VEGF dilated ear arteries but not veins, and laser Doppler velocimetry showed that VEGF quickly increased tissue blood flow along with arterial dilation. Whole-mount immunostaining showed that VEGF phosphorylated endothelial nitric oxide synthase (eNOS) at residue Ser1177 and disrupted the alignment of vascular endothelial-cadherin (VE-cadherin) around the endothelial cell borders in mouse ear skin, indicating endothelial nitric oxide (NO) production and barrier disruption. Administration of the nitric oxide synthesis inhibitor, L-NAME, as well as the vasoconstrictor phenylephrine, abolished all VEGF-induced responses, including blood flow increase, dye leakage, and tissue swelling. However, these two treatments did not alter the intracellular localization of VE-cadherin-induced by VEGF. These observations underscore the importance of vascular dilation and, subsequent increase in blood flow, as well as, endothelial barrier disruption in the mechanisms of VEGF-induced vascular hyper-permeability.
authors.affiliation: Department of Animal Radiology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Ashina
authors.affiliation: Department of Animal Radiology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Tsubosaka
authors.affiliation: Department of Animal Radiology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Animal Radiology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Omori
authors.affiliation: Department of Animal Radiology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan. Electronic address: amurata@mail.ecc.u-tokyo.ac.jp.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Murata
mesh_terms: D000818:Animals; D001775:Blood Circulation / Q000502:physiology*; D002199:Capillary Permeability / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology; D051379:Mice; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000502:physiology*
chemical_list: D042461:Vascular Endothelial Growth Factor A; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases
keywords: Blood flow; Endothelial barrier; Nitric oxide; VEGF; Vascular permeability