title: Luminal endothelial lectins with affinity for N-acetylglucosamine determine flow-induced cardiac and vascular paracrine-dependent responses.
abstract: Coronary blood flow applied to the endothelial lumen modulates parenchymal functions via paracrine effectors, but the mechanism of flow sensation is unknown. We and others have demonstrated that coronary endothelial luminal membrane (CELM) oligosaccharides and lectins are involved in flow detection, and we proposed that cardiac effects of coronary flow result from a reversible flow-modulated lectin-oligosaccharide interaction. Recently, glycosylated and amiloride-sensitive Na(+)/Ca(++) channels (ENaCs) have been proposed to be involved in the flow-induced endothelial responses. Because N-acetylglucosamine (GlcNac) is one of the main components of glycocalyx oligosaccharides (i.e., hyaluronan [-4GlcUAbeta1-3GlcNAcbeta1-](n)), the aim of this article is to isolate and define CELM GlcNac-binding lectins and determine their role in cardiac and vascular flow-induced effects. For this purpose, we synthesized a 460-kDa GlcNac polymer (GlcNac-Pol) with high affinity toward GlcNac-recognizing lectins. In the heart, intracoronary administration of GlcNac-Pol upon binding to CELM diminishes the flow-dependent positive inotropic and dromotropic effects. Furthermore, GlcNac-Pol was used as an affinity probe to isolate CELM GlcNac-Pol-recognizing lectins and at least 35 individual lectinic peptides were identified, one of them the beta-ENaC channel. Some of these lectins could participate in flow sensing and in GlcNac-Pol-induced effects. We also adopted a flow-responsive and well-accepted model of endothelial-parenchymal paracrine interaction: isolated blood vessels perfused at controlled flow rates. We established that flow-induced vasodilatation (FIV) is blocked by endothelial luminal membrane (ELM) bound GlcNac-Pol, nitro-l-arginine methyl ester and indomethacin, amiloride, and hyaluronidase. The effect of hyaluronidase was reversed by infusion of soluble hyaluronan. These results indicate that GlcNac-Pol inhibits FIV by competing and displacing intrinsic hyaluronan bound to a lectinic structure such as the amiloride-sensitive ENaC. Nitric oxide and prostaglandins are the putative paracrine mediators of FIV.
authors.affiliation: Departamento de Fisiologia, Universidad Autonoma de San Luis Potosi, San Luis Potosi, Mexico.
authors.forename: Juan
authors.initials: J
authors.lastname: Ramiro-Diaz
authors.forename: Alma
authors.initials: A
authors.lastname: Barajas-Espinosa
authors.forename: Erika
authors.initials: E
authors.lastname: Chi-Ahumada
authors.forename: Sandra
authors.initials: S
authors.lastname: Perez-Aguilar
authors.forename: David
authors.initials: D
authors.lastname: Torres-Tirado
authors.forename: Jesus
authors.initials: J
authors.lastname: Castillo-Hernandez
authors.forename: Maureen
authors.initials: M
authors.lastname: Knabb
authors.forename: Ana Barba
authors.initials: AB
authors.lastname: de Rosa
authors.forename: Rafael
authors.initials: R
authors.lastname: Rubio
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism*; D000818:Animals; D002846:Chromatography, Affinity; D003326:Coronary Circulation / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology*; D006168:Guinea Pigs; D037102:Lectins / Q000378:metabolism*; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology; D009206:Myocardium / Q000378:metabolism*; D014664:Vasodilation / Q000502:physiology
chemical_list: D037102:Lectins; D000117:Acetylglucosamine