Chronic hyperglycemia underlies microvascular complications in patients with type 1 diabetes. The mechanisms leading to these vascular complications are not fully understood. Recently, we observed that acute hyperglycemia results in endothelial glycocalyx damage. To establish whether glycocalyx is associated with microvascular damage, we performed glycocalyx perturbation volume measurements in type 1 diabetic patients with microalbuminuria (DM1-MA group; n ‫؍‬ 7), without microalbuminuria (DM1-NA group; n ‫؍‬ 7), and in age-matched control subjects (CON; n ‫؍‬ 7). Systemic glycocalyx volume was determined comparing intravascular distribution volume of a glycocalyxpermeable tracer (dextran 40) to that of a glycocalyximpermeable tracer (labeled erythrocytes). Sublingual capillaries were visualized using orthogonal polarization spectral microscopy to estimate microvascular glycocalyx. Patients and control subjects were matched according to age and BMI. Glycocalyx volume decreased in a stepwise fashion from CON, DM1-NA, and finally DM1-MA subjects (1.5 ؎ 0.1, 0.8 ؎ 0.4, and 0.2 ؎ 0.1 l, respectively, P < 0.05). Microvascular glycocalyx in sublingual capillaries was also decreased in type 1 diabetes versus the control group (0.5 ؎ 0.1 vs. 0.9 ؎ 0.1 m, P < 0.05). Plasma hyaluronan, a principal glycocalyx constituent, and hyaluronidase were increased in type 1 diabetes. In conclusion, type 1 diabetic patients are characterized by endothelial glycocalyx damage, the severity of which is increased in presence of microalbuminuria.

Myocardial tissue edema attributable to increased microvascular fluid loss contributes to cardiac dysfunction after myocardial ischemia, cardiopulmonary bypass, hypertension, and sepsis. Recent studies suggest that carbohydrate structures on the luminal surface of microvascular endothelium are essential to prevent tissue edema. We carefully preserved these structures for visualization with electron microscopy, revealing that the rat myocardial capillary endothelial surface is coated with a 0.2-to 0.5-m-thick carbohydrate layer and that its degradation instantly results in notable myocardial tissue edema.

Objective-A thick endothelial glycocalyx provides the endothelial surface with a nonadherent shield. Oxidized LDL (Ox-LDL) degrades the endothelial glycocalyx. We hypothesized that glycocalyx degradation stimulates leukocyteendothelial cell adhesion, whereas intravascular supplementation with sulfated polysaccharides reconstitutes the endothelial glycocalyx and attenuates Ox-LDL-induced leukocyte-endothelial cell adhesion. Methods and Results-Degradation of the endothelial glycocalyx by local microinjection of heparitinase (10 to 50 U/mL) into mouse cremaster venules dose-dependently increased the number of adherent leukocytes. Systemic administration of Ox-LDL (0.4 mg/100 g body weight) induced 10.1Ϯ0.9 adherent leukocytes/100 m at 60 minutes. In the venules perfused with 500-kDa dextran sulfate (1 mg/mL), the number of adherent leukocytes at 60 minutes after Ox-LDL bolus application was not influenced (9.2Ϯ1.0 leukocytes/100 m). However, the venules locally perfused with heparan sulfate (10 mg/mL) or heparin (1 mg/mL) displayed a significantly lower number of adherent leukocytes induced by Ox-LDL: 5.1Ϯ0.7 and 5.4Ϯ0.9 leukocytes/100 m, respectively (PϽ0.05). Fluorescently labeled heparan sulfate and heparin, but not dextran sulfate, attached to the venule luminal surface after Ox-LDL administration. Key Words: glycocalyx Ⅲ leukocytes Ⅲ oxidized LDL Ⅲ heparin T he endothelial glycocalyx provides the endothelial surface with a negatively charged coating that contributes to the antiadhesive nature of the endothelial cell surface. 1,2 In the presence of inflammatory stimuli, the endothelial surface loses its nonadhesiveness because of the activation of adhesion molecules and becomes accessible to leukocytes. There is evidence that activation of adhesion molecules is associated with changes in the cell-surface glycocalyx. 2-4 Indeed, the glycocalyx occupies a large domain at the endothelial surface, 5,6 which most probably influences the adhesion process. In this investigation, we studied the effect of endothelial glycocalyx condition on leukocyte-endothelial cell adhesion. Conclusions-EndothelialUnderstanding the role of the endothelial glycocalyx in leukocyte-endothelial cell adhesion has direct relevance for atherosclerosis-related conditions, such as hypercholesterolemia and the plasma presence of oxidized lipoproteins, which are associated with increased leukocyte recruitment 7,8 and degradation of the endothelial glycocalyx. 9 -11 Noteworthy, early modifications of endothelial cells during diet-induced hypercholesterolemia are represented by a decreased thickness and anionic charge of the endothelial glycocalyx and by changes in its biochemical composition. 9,10 Degradation of the endothelial glycocalyx is also induced by oxidized LDL (Ox-LDL in clinically relevant doses and is associated with a parallel increase in endothelial surface adhesiveness. 11 The first aim of the present study was to induce a primary alteration of the thickness and charge of the endothelial glycocalyx by enzyme treatment and to inves...

Endothelium-derived nitric oxide (NO) is synthesized in response to chemical and physical stimuli. Here, we investigated a possible role of the endothelial cell glycocalyx as a biomechanical sensor that triggers endothelial NO production by transmitting flow-related shear forces to the endothelial membrane. Isolated canine femoral arteries were perfused with a Krebs-Henseleit solution at a wide range of perfusion rates with and without pretreatment with hyaluronidase to degrade hyaluronic acid glycosaminoglycans within the glycocalyx layer. NO production rate was evaluated as the product of nitrite concentration in the perfusate and steady-state perfusion rate. The slope that correlates the linear relation between perfusion rate and NO production rate was taken as a measure for flow-induced NO production. Hyaluronidase treatment significantly decreased flow-induced NO production to 19 +/- 9% of control (mean +/- SD; P < 0.0001 vs. control; n = 11), whereas it did not affect acetylcholine-induced NO production (88 +/- 17% of pretreatment level, P = not significant; n = 10). We conclude that hyaluronic acid glycosaminoglycans within the glycocalyx play a pivotal role in detecting and amplifying the shear force of flowing blood that triggers endothelium-derived NO production in isolated canine femoral arteries.