title: Reactive oxygen species mediate modification of glycocalyx during ischemia-reperfusion injury.
abstract: The glycocalyx (Gcx) is a complex and poorly understood structure covering the luminal surface of endothelial cells. It is known to be a determinant of vascular rheology and permeability and may be a key control site for the vascular injuries caused by ischemia-reperfusion (I/R). We used intravital-microscopy to evaluate the effects of I/R injury on two properties of Gcx in mouse cremasteric microvessels: exclusion of macromolecules (anionic-dextrans) and intracapillary distribution of red blood cells (RBC). In this model, the Gcx is rapidly modified by I/R injury with an increase in 70-kDa anionic-dextran penetration without measurable effect on the penetration of 580-kDa anionic-dextran or on RBC exclusion. The effects of I/R injury appear to be mediated by the rapid production of reactive oxygen species (ROS) because they are ameliorated by the addition of exogenous superoxide dismutase-catalase. Intravenous application of allopurinol or heparin also inhibited the effects of I/R injury, and we interpret efficacy of allopurinol as evidence for a role for xanthine-oxidoreductase (XOR) in the response to I/R injury. Heparin, which is hypothesized to displace XOR from a heparin-binding domain in the Gcx, reduced the effects of I/R. The effects of I/R injury were also partially prevented or fully reversed by the intravascular infusion of exogenous hyaluronan. These data demonstrate: 1) the liability of Gcx during I/R injury; 2) the importance of locally produced ROS in the injury to Gcx; and 3) the potential importance of heparin-binding sites in modulating the ROS production. Our findings further highlight the relations between glycosaminoglycans and the pathophysiology of Gcx in vivo.
authors.affiliation: Cardiovascular Research Center, Dept. of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 409 Lane Road, Charlottesville, VA 22908, USA.
authors.forename: Ivan
authors.initials: I
authors.lastname: Rubio-Gayosso
authors.forename: Steven H
authors.initials: SH
authors.lastname: Platts
authors.forename: Brian R
authors.initials: BR
authors.lastname: Duling
mesh_terms: D000818:Animals; D002196:Capillaries / Q000187:drug effects / Q000502:physiology; D042783:Endothelial Cells / Q000502:physiology; D019276:Glycocalyx / Q000187:drug effects / Q000502:physiology*; D006493:Heparin / Q000378:metabolism; D006820:Hyaluronic Acid / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation / Q000502:physiology; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012039:Regional Blood Flow / Q000502:physiology; D015427:Reperfusion Injury / Q000503:physiopathology*; D014664:Vasodilation / Q000502:physiology; D014970:Xanthines / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D014970:Xanthines; D006820:Hyaluronic Acid; D006493:Heparin