Mannose polymer induces vasodilation through a luminal mannose receptor in rat mesenteric arteries

Several of the luminal endothelial glycocalyx functions are exerted via interactions with glycosidic components and sugar binding proteins with lectinic activity. One important example is the mannose receptor (MR). The MR has been detected in cell types that mediate the phagocytosis and pinocytosis of particles and solutes containing mannose. Using isolated constant pressurized rat mesenteric arteries (RMA), we evaluated the effects of a mannose polymer in the vascular tone. RMA were precontracted with 10μmol/L phenylephrine and carbohydrates were perfused at 20μl/min. Perfusion of free D-mannose [1nmol/L to 100μmol/L] induced a concentrationdependent vasodilation of pre-contracted RMA. Perfusion of mannose polymer [1nmol/L to 100μmol/L] induced a larger effect in a concentration-dependent vasodilation. Mannose polymer's maximum effect reached a 96% of basal diameter; this significant vasodilation was not nitric oxide (NO) or cyclooxygenase (COX) dependent effect. We corroborated the binding of the mannose polymer to the endothelial lumen, by perfusion of a fluorescently labeled mannose polymer; and also, we detected a significant level of MR mRNA in whole mesenteric arteries. With all these, we proposed a novel effect of a MR in the regulation of vascular tone.