Exogenous nitric oxide requires an endothelial glycocalyx to prevent postischemic coronary vascular leak in guinea pig hearts

Clinic of Anesthesiology, Ludwig-Maximilians-University, Marchioninistrasse 15, 81377 Munich, Germany.
Critical care (London, England) (Impact Factor: 4.48). 06/2008; 12(3):R73. DOI: 10.1186/cc6913
Source: PubMed

ABSTRACT Postischemic injury to the coronary vascular endothelium, in particular to the endothelial glycocalyx, may provoke fluid extravasation. Shedding of the glycocalyx is triggered by redox stress encountered during reperfusion and should be alleviated by the radical scavenger nitric oxide (NO). The objective of this study was to investigate the effect of exogenous administration of NO during reperfusion on both coronary endothelial glycocalyx and vascular integrity.
Isolated guinea pig hearts were subjected to 15 minutes of warm global ischemia followed by 20 minutes of reperfusion in the absence (Control group) and presence (NO group) of 4 microM NO. In further experiments, the endothelial glycocalyx was enzymatically degraded by means of heparinase followed by reperfusion without (HEP group) and with NO (HEP+NO group).
Ischemia and reperfusion severely damaged the endothelial glycocalyx. Shedding of heparan sulfate and damage assessed by electron microscopy were less in the presence of NO. Compared with baseline, coronary fluid extravasation increased after ischemia in the Control, HEP, and HEP+NO groups but remained almost unchanged in the NO group. Tissue edema was significantly attenuated in this group. Coronary vascular resistance rose by 25% to 30% during reperfusion, but not when NO was applied, irrespective of the state of the glycocalyx. Acute postischemic myocardial release of lactate was comparable in the four groups, whereas release of adenine nucleotide catabolites was reduced 42% by NO. The coronary venous level of uric acid, a potent antioxidant and scavenger of peroxynitrite, paradoxically decreased during postischemic infusion of NO.
The cardioprotective effect of NO in postischemic reperfusion includes prevention of coronary vascular leak and interstitial edema and a tendency to forestall both no-reflow and degradation of the endothelial glycocalyx.

Download full-text


Available from: Bernhard F Becker, Sep 29, 2015
33 Reads
  • Source
    • "Nanomechanical changes induced by TNF-α and thrombin, respectively, were identical to those seen after LPS exposure, suggesting that glycocalyx deterioration is not confined to endotoxemia, but probably occurs across the whole spectrum of critical illness. Consistent with this notion, increased plasma levels of shed glycocalyx constituents have been reported in patients with major trauma [54], acute lung injury [53], and after major vascular surgery with global or regional ischemia [55,56]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The endothelial glycocalyx (eGC), a carbohydrate-rich layer lining the luminal side of the endothelium, regulates vascular adhesiveness and permeability. Although central to the pathophysiology of vascular barrier dysfunction in sepsis, glycocalyx damage has been generally understudied, in part because of the aberrancy of in vitro preparations and its degradation during tissue handling. The aim of this study was to analyze inflammation-induced damage of the eGC on living endothelial cells by atomic-force microscopy (AFM) nanoindentation technique. AFM revealed the existence of a mature eGC on the luminal endothelial surface of freshly isolated rodent aorta preparations ex vivo, as well as on cultured human pulmonary microvascular endothelial cells (HPMEC) in vitro. AFM detected a marked reduction in glycocalyx thickness (266 ± 12 vs. 137 ± 17 nm, P<0.0001) and stiffness (0.34 ± 0.03 vs. 0.21 ± 0.01 pN/mn, P<0.0001) in septic mice (1 mg E. coli lipopolysaccharides (LPS)/kg BW i.p.) compared to controls. Corresponding in vitro experiments revealed that sepsis-associated mediators, such as thrombin, LPS or Tumor Necrosis Factor-α alone were sufficient to rapidly decrease eGC thickness (-50%, all P<0.0001) and stiffness (-20% P<0.0001) on HPMEC. In summary, AFM nanoindentation is a promising novel approach to uncover mechanisms involved in deterioration and refurbishment of the eGC in sepsis.
    PLoS ONE 11/2013; 8(11):e80905. DOI:10.1371/journal.pone.0080905 · 3.23 Impact Factor
  • Source
    • "Ischemia/reperfusion injury can stimulate shedding of the glycocalyx [12]. Although the exact mechanism triggering ischemia/reperfusion glycocalyx disruption is unknown, it is believed that increased free radical production along with TNF-α and mast cell degranulation may combine to induce shedding and enzymatic degradation of the glycocalyx [10] [51] [52] [86]. In addition, HA and CD44 expression are upregulated in the microvascular endothelium during ischemia/reperfusion [87] [88]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Vascular integrity or the maintenance of blood vessel continuity is a fundamental process regulated, in part, by the endothelial glycocalyx and cell-cell junctions. Defects in endothelial barrier function are an initiating factor in several disease processes including atherosclerosis, ischemia/reperfusion, tumor angiogenesis, cancer metastasis, diabetes, sepsis and acute lung injury. The glycosaminoglycan, hyaluronan (HA), maintains vascular integrity through endothelial glycocalyx modulation, caveolin-enriched microdomain regulation and interaction with endothelial HA binding proteins. Certain disease states increase hyaluronidase activity and reactive oxygen species (ROS) generation which break down high molecular weight HA to low molecular weight fragments causing damage to the endothelial glycocalyx. Further, these HA fragments can activate specific HA binding proteins upregulated in vascular disease to promote actin cytoskeletal reorganization and inhibition of endothelial cell-cell contacts. This review focuses on the crucial role of HA in vascular integrity and how HA degradation promotes vascular barrier disruption.
    American Journal of Cardiovascular Disease 01/2011; 1(3):200-13.
  • Source
    • "These studies showed that the glycocalyx constitutes a voluminous intravascular barrier for flowing blood and macromolecules [3], and that enzymatic glycocalyx degradation is associated with an increased adhesiveness of the endothelium for platelets and leucocytes [4] and with an impaired nitric oxide (NO)-mediated shear-dependent vasodilation of arterioles [5]. In addition, glycocalyx treatment in isolated hearts was demonstrated to result in an increased fluid leakage [6,7], underlying the contribution of the glycocalyx to the vascular permeability barrier in conjunction with the endothelial cells (double barrier concept [1,7]). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Myocardial edema is a hallmark of ischemia-reperfusion-related cardiac injury. Ischemia-reperfusion has been shown to result in degradation of the endothelial glycocalyx. The glycocalyx is the gel-like mesh of polysaccharide structures and absorped plasma proteins on the luminal side of the vasculature, and in the past decade has been shown to play an important role in protection of the vessel wall, including its barrier properties. Prevention of glycocalyx loss or restoration of a damaged glycocalyx may be a promising therapeutic target during clinical procedures involving ischemia-reperfusion.
    Critical care (London, England) 07/2008; 12(4):167. DOI:10.1186/cc6939 · 4.48 Impact Factor
Show more