Short-term hyperglycemia increases endothelial glycocalyx permeability and acutely decreases lineal density of capillaries with flowing red blood cells

Abstract

Zuurbier, Coert J., Cihan Demirci, Anneke Koeman, Hans Vink, and Can Ince. Short-term hyperglycemia increases endothelial glycocalyx permeability and acutely decreases lineal density of capillaries with flowing red blood cells. J Appl Physiol 99: [1471][1472][1473][1474][1475][1476] 2005. First published July 14, 2005; doi:10.1152/japplphysiol.00436.2005.-Hyperglycemia is becoming recognized as an important risk factor for microvascular dysfunction. We hypothesized that short-term hyperglycemia, either on the scale of hours or weeks, alters the barrier function and the volume of the endothelial glycocalyx and decreases functional capillary density and deformability of the red blood cells (RBCs). All experiments were performed in anesthetized, mechanically ventilated, C57BL/6 mice that were either normoglycemic, acutely hyperglycemic (25 mM) for 60 min due to infusion of glucose, or hyperglycemic (25 mM) for 2-4 wk (db/db mice). The glycocalyx was probed using 40-kDa Texas red dextran, which is known to permeate the glycocalyx, and 70-kDa FITC dextran, which has impaired access to the glycocalyx in healthy animals. Clearance of the dye from the blood was measured. An orthogonal polarization spectral imaging technique was used to visualize the number of capillaries with flowing RBCs of the dorsal flexor muscle. The data indicate that short-term hyperglycemia causes a rapid decrease of the ability of the glycocalyx to exclude 70-kDa dextran. No change in the vascular permeation of 40-kDa dextran was observed. Glycocalyx volume was not affected by short-term hyperglycemia. In addition, 1 h of hyperglycemia resulted in a 38% decrease of the lineal density of capillaries with flowing RBCs. This decreased lineal density was not observed in the 2-to 4-wk hyperglycemia model. Short-term hyperglycemia was without any effect on the deformablity of the RBCs. The data indicate that the described increased vascular permeability with hyperglycemia can be ascribed to an increased permeability of the glycocalyx, identifying the glycocalyx as a potential early target of hyperglycemia. vascular permeability; diabetes; skeletal muscle; db/db mice HYPERGLYCEMIA, EITHER IN ITS acute form, such as which may occur in hospitalized critically ill patients, or in its chronic form, such as is present in patients with diabetes mellitus, is associated with increased rates of morbidity and mortality and diminished clinical outcome. The central importance of a vascular pathology underlying the hyperglycemia-associated poor prognosis is becoming increasingly evident. Characteristics of hyperglycemia-induced vasculopathy include decreased endothelium-dependent vasodilation, increased capillary permeability for large proteins such as albumin, swelling of endothelial cells, decreased capillary dimensions and diameters, and thickening of the basal lamina (5,13,20,23,33,41).The endothelial cell glycocalyx, a 0.2-to 0.5-m matrix lining the luminal surface of all blood vessels, is a significant factor in microvascular regulation by its action on volum...

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