Editing Glycocalyx (section)

==In vascular endothelial tissue==

The glycocalyx is located on the [[apical membrane|apical]] surface of vascular endothelial cells which line the [[Lumen (anatomy)|lumen]]. When vessels are stained with cationic dyes such as [[Alcian blue stain]], [[transmission electron microscopy]] shows a small, irregularly shaped layer extending approximately 50–100&nbsp;nm into the lumen of a blood vessel.  Another study used [[osmium tetroxide]] staining during freeze substitution, and showed that the endothelial glycocalyx could be up to 11 μm thick.<ref>{{cite journal|last=Ebong|first=Eno|author2=Macaluso FP |author3=Spray DC |author4=Tarbell JM |title=Imaging the Endothelial Glycocalyx In Vitro By Rapid Freezing/Freeze Substitution Transmission Electron Microscopy|journal=Arteriosclerosis, Thrombosis, and Vascular Biology|date=August 2011|volume=31|issue=8|pages=1908–1915|doi=10.1161/ATVBAHA.111.225268|pmc=3141106 |pmid=21474821}}</ref> It is present throughout a diverse range of microvascular beds (capillaries) and macrovessels (arteries and veins).  The glycocalyx also consists of a wide range of enzymes and proteins that regulate [[leukocyte]] and [[thrombocyte]] adherence, since its principal role in the vasculature is to maintain plasma and vessel-wall homeostasis.  These enzymes and proteins include:
*Endothelial nitric oxide synthase ([[endothelial NOS]])
*Extracellular superoxide dismutase ([[SOD3]])
*[[Angiotensin converting enzyme]]
*[[Antithrombin]]-III
*[[Lipoprotein lipase]]
*[[Apolipoproteins]]
*[[Growth factors]]
*[[Chemokines]]

The enzymes and proteins listed above serve to reinforce the glycocalyx barrier against vascular and other diseases.  Another main function of the glycocalyx within the vascular endothelium is that it shields the vascular walls from direct exposure to blood flow, while serving as a vascular permeability barrier.<ref>Van de Berg, Bernard M., Max Nieuwdorp, Erik S.G. Stroes, Hans Vink.  "Glycocalyx and endothelial (dys) function:  from mice to men."  Pharmacological Reports, 2006, 57: 75-80.</ref>  Its protective functions are universal throughout the vascular system, but its relative importance varies depending on its exact location in the vasculature.  In microvascular tissue, the glycocalyx serves as a vascular permeability barrier by inhibiting coagulation and leukocyte adhesion.  Leukocytes must not stick to the vascular wall because they are important components of the [[immune system]] that must be able to travel to a specific region of the body when needed.  In arterial vascular tissue, the glycocalyx also inhibits coagulation and leukocyte adhesion, but through mediation of [[shear stress]]-induced nitric oxide release.  Another protective function throughout the cardiovascular system is its ability to affect the filtration of [[interstitial fluid]] from capillaries into the interstitial space.<ref>Drake-Holland, Angela & Mark Noble. "The Important New Drug Target in Cardiovascular Medicine – the Vascular Glycocalyx." Cardiovascular & Hematological Disorders-Drug Targets, 2009, 9, p. 118-123</ref>

The glycocalyx, which is located on the [[apical membrane|apical]] surface of [[endothelial]] cells, is composed of a negatively charged network of [[proteoglycan]]s, glycoproteins, and glycolipids.<ref>Van de Berg, Bernard M., Max Nieuwdorp, Erik S.G. Stroes, Hans Vink.  Glycocalyx and endothelial (dys) function:  from mice to men.  Pharmacological Reports, 2006, 57: 75-80.</ref> Along the luminal surface of the vascular glycocalyx exists an empty layer that excludes red blood cells.<ref>{{cite journal |last1=Reitsma |first1=Sietze |last2=Slaaf |first2=Dick W. |last3=Vink |first3=Hans |last4=van Zandvoort |first4=Marc A. M. J. |last5=oude Egbrink |first5=Mirjam G. A. |title=The endothelial glycocalyx: composition, functions, and visualization |journal=Pflügers Archiv: European Journal of Physiology |date=June 2007 |volume=454 |issue=3 |pages=345–359 |doi=10.1007/s00424-007-0212-8|pmid=17256154 |pmc=1915585 }}</ref>