title: Direct visualization of the arterial wall water permeability barrier using CARS microscopy.
abstract: The artery wall is equipped with a water permeation barrier that allows blood to flow at high pressure without significant water leak. The precise location of this barrier is unknown despite its importance in vascular function and its contribution to many vascular complications when it is compromised. Herein we map the water permeability in intact arteries, using coherent anti-Stokes Raman scattering (CARS) microscopy and isotopic perfusion experiments. Generation of the CARS signal is optimized for water imaging with broadband excitation. We identify the water permeation barrier as the endothelial basolateral membrane and show that the apical membrane is highly permeable. This is confirmed by the distribution of the AQP1 water channel within endothelial membranes. These results indicate that arterial pressure equilibrates within the endothelium and is transmitted to the supporting basement membrane and internal elastic lamina macromolecules with minimal deformation of the sensitive endothelial cell. Disruption of this pressure transmission could contribute to endothelial cell dysfunction in various pathologies.
authors.affiliation: Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, MD 20892.
authors.forename: Bertrand M
authors.initials: BM
authors.lastname: Lucotte
authors.affiliation: Vascular Pharmacology Research Group, Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom.
authors.forename: Chloe
authors.initials: C
authors.lastname: Powell
authors.affiliation: Laboratory of Optical Spectroscopy, NHLBI, NIH, Bethesda, MD 20892.
authors.forename: Jay R
authors.initials: JR
authors.lastname: Knutson
authors.affiliation: Light Microscopy Core, NHLBI, NIH, Bethesda, MD 20892.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Combs
authors.affiliation: Light Microscopy Core, NHLBI, NIH, Bethesda, MD 20892.
authors.forename: Daniela
authors.initials: D
authors.lastname: Malide
authors.affiliation: Pathology Core, NHLBI NIH, Bethesda, MD 20892.
authors.forename: Zu-Xi
authors.initials: ZX
authors.lastname: Yu
authors.affiliation: Laboratory of Kidney and Electrolyte Metabolism, NHLBI, NIH, Bethesda, MD 20892.
authors.forename: Mark
authors.initials: M
authors.lastname: Knepper
authors.affiliation: Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, MD 20892.
authors.forename: Keval D
authors.initials: KD
authors.lastname: Patel
authors.affiliation: Dunn School Electron Microscopy Facility, University of Oxford, Oxford OX1 3RE, United Kingdom.
authors.forename: Anna
authors.initials: A
authors.lastname: Pielach
authors.affiliation: Dunn School Electron Microscopy Facility, University of Oxford, Oxford OX1 3RE, United Kingdom.
authors.forename: Errin
authors.initials: E
authors.lastname: Johnson
authors.affiliation: Vascular Pharmacology Research Group, Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom.
authors.forename: Lyudmyla
authors.initials: L
authors.lastname: Borysova
authors.affiliation: Vascular Pharmacology Research Group, Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom.
authors.forename: Kim A
authors.identifier: 0000-0002-8014-2775
authors.initials: KA
authors.lastname: Dora
authors.affiliation: Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, MD 20892; rsb@nih.gov.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Balaban
mesh_terms: D000818:Animals; D051398:Aquaporin 1 / Q000378:metabolism*; D001158:Arteries / Q000000981:diagnostic imaging / Q000378:metabolism; D002199:Capillary Permeability; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000378:metabolism; D008297:Male; D000073758:Nonlinear Optical Microscopy; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C496022:Aqp1 protein, rat; D051398:Aquaporin 1
keywords: Raman spectroscopy; blood flow; multiphoton microscopy; superresolution microscopy; water permeation