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Ertmer C, Rehberg S, Van Aken H, Westphal M. Relevance of non-albumin colloids in intensive care medicine. Best Pract Res Clin Anaesthesiol 2009; 23:193-212. [PMID: 19653439 DOI: 10.1016/j.bpa.2008.11.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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152
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Chappell D, Jacob M, Paul O, Rehm M, Welsch U, Stoeckelhuber M, Conzen P, Becker BF. The glycocalyx of the human umbilical vein endothelial cell: an impressive structure ex vivo but not in culture. Circ Res 2009; 104:1313-7. [PMID: 19423849 DOI: 10.1161/circresaha.108.187831] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Potter and Damiano recently assessed the hydrodynamic dimensions of the endothelial glycocalyx in vivo (mouse cremaster muscle venules) and in vitro (human umbilical vein and bovine aorta endothelium cultured in perfused microchannels) using fluorescent microparticle image velocimetry (Circ Res. 2008;102:770-776). Great discrepancy was observed, the glycocalyx presenting a zone of interaction extending approximately 0.52 microm into the vessel lumen in vivo, but only 0.02 to 0.03 microm from cultured cells. In an accompanying editorial, Barakat cautioned that the difference in hydrodynamic interaction did not allow one to conclude that the cultured cells totally lack a physical cell surface layer capable of mechanotransduction (Circ Res. 2008;102:747-748). To stabilize the glycocalyx for electron microscopic investigation, we perfusion-fixed 6 human umbilical veins and confluent and nonconfluent cultures (5 each) of human umbilical vein endothelial cells (HUVECs) with lanthanum/glutaraldehyde solution. Ex vivo, the thickness of glycocalyx of umbilical vein endothelium averaged 878 nm. HUVECs in vitro presented a glycocalyx with a dense-zone thickness of only 29.4 nm, plus sparse filaments reaching out on average to 118 nm, there being no difference between the nonconfluent and confluent cells. Immunohistology demonstrated the presence of heparan sulfates and syndecan-1, main constituents of the glycocalyx, both ex vivo and in vitro. These results support the observed discrepancy between glycocalyx thickness in vivo and in vitro, now for one and the same type of human cell. The presence of heparan sulfates and syndecan-1 also on cultured cells may explain why mechanotransduction phenomena can be observed even with a nonmature glycocalyx.
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Affiliation(s)
- Daniel Chappell
- Clinic of Anesthesiology, Ludwig-Maximilians-University, Nussbaumstrasse 20, 80336 Munich, Germany.
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153
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Albumin Augmentation Improves Condition of Guinea Pig Hearts After 4 hr of Cold Ischemia. Transplantation 2009; 87:956-65. [DOI: 10.1097/tp.0b013e31819c83b5] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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154
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Die Bedeutung der endothelialen Glykokalyx für die Infusionspraxis in der Notfallmedizin. Notf Rett Med 2009. [DOI: 10.1007/s10049-008-1146-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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155
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Chappell D, Jacob M, Hofmann-Kiefer K, Rehm M, Welsch U, Conzen P, Becker BF. Antithrombin reduces shedding of the endothelial glycocalyx following ischaemia/reperfusion. Cardiovasc Res 2009; 83:388-96. [DOI: 10.1093/cvr/cvp097] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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TNF-α induced shedding of the endothelial glycocalyx is prevented by hydrocortisone and antithrombin. Basic Res Cardiol 2008; 104:78-89. [DOI: 10.1007/s00395-008-0749-5] [Citation(s) in RCA: 212] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Accepted: 08/22/2008] [Indexed: 01/30/2023]
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158
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Sutton TA. Alteration of microvascular permeability in acute kidney injury. Microvasc Res 2008; 77:4-7. [PMID: 18938184 DOI: 10.1016/j.mvr.2008.09.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 09/03/2008] [Indexed: 10/21/2022]
Abstract
Functional and structural abnormalities in the renal microvasculature are important processes contributing to the pathophysiology of ischemic acute kidney injury (AKI). Renewed interest in the complex interplay between tubular injury, inflammation and microvascular alterations has emerged in order to gain a better understanding of acute kidney injury syndromes. This review examines alterations of the renal microvasculature as they relate to ischemic and septic AKI with an emphasis on the mechanisms involved in altered microvascular permeability.
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Affiliation(s)
- Timothy A Sutton
- Division of Nephrology, Department of Medicine, Indiana Center for Biological Microscopy, Indiana University School of Medicine, 950 West Walnut Street R-II, 202 Indianapolis, IN 46202, USA.
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159
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Chappell D, Jacob M, Becker B, Hofmann-Kiefer K, Conzen P, Rehm M. Expedition Glykokalyx. Anaesthesist 2008; 57:959-69. [DOI: 10.1007/s00101-008-1445-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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160
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VanTeeffelen JWGE. How to prevent leaky vessels during reperfusion? Just keep that glycocalyx sealant in place! CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2008; 12:167. [PMID: 18638363 PMCID: PMC2575556 DOI: 10.1186/cc6939] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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.
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161
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Bruegger D, Rehm M, Jacob M, Chappell D, Stoeckelhuber M, Welsch U, Conzen P, Becker BF. Exogenous nitric oxide requires an endothelial glycocalyx to prevent postischemic coronary vascular leak in guinea pig hearts. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2008; 12:R73. [PMID: 18518977 PMCID: PMC2481466 DOI: 10.1186/cc6913] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 03/19/2008] [Accepted: 06/02/2008] [Indexed: 01/28/2023]
Abstract
Introduction 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. Methods 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 μM 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). Results 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. Conclusion 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.
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Affiliation(s)
- Dirk Bruegger
- Clinic of Anesthesiology, Ludwig-Maximilians-University, Marchioninistrasse 15, 81377 Munich, Germany.
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162
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Meyer W, Godynicki S, Tsukise A. Lectin histochemistry of the endothelium of blood vessels in the mammalian integument, with remarks on the endothelial glycocalyx and blood vessel system nomenclature. Ann Anat 2008; 190:264-76. [DOI: 10.1016/j.aanat.2007.11.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Revised: 10/25/2007] [Accepted: 11/11/2007] [Indexed: 11/16/2022]
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163
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Satchell SC, Tooke JE. What is the mechanism of microalbuminuria in diabetes: a role for the glomerular endothelium? Diabetologia 2008; 51:714-25. [PMID: 18347777 PMCID: PMC2292427 DOI: 10.1007/s00125-008-0961-8] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Accepted: 12/20/2007] [Indexed: 12/11/2022]
Abstract
Microalbuminuria is an important risk factor for cardiovascular disease and progressive renal impairment. This holds true in the general population and particularly in those with diabetes, in whom it is common and marks out those likely to develop macrovascular disease and progressive renal impairment. Understanding the pathophysiological mechanisms through which microalbuminuria occurs holds the key to designing therapies to arrest its development and prevent these later manifestations. Microalbuminuria arises from the increased passage of albumin through the glomerular filtration barrier. This requires ultrastructural changes rather than alterations in glomerular pressure or filtration rate alone. Compromise of selective glomerular permeability can be confirmed in early diabetic nephropathy but does not correlate well with reported glomerular structural changes. The loss of systemic endothelial glycocalyx--a protein-rich surface layer on the endothelium--in diabetes suggests that damage to this layer represents this missing link. The epidemiology of microalbuminuria reveals a close association with systemic endothelial dysfunction and with vascular disease, also implicating glomerular endothelial dysfunction in microalbuminuria. Our understanding of the metabolic and hormonal sequelae of hyperglycaemia is increasing, and we consider these in the context of damage to the glomerular filtration barrier. Reactive oxygen species, inflammatory cytokines and growth factors are key players in this respect. Taken together with the above observations and the presence of generalised endothelial dysfunction, these considerations lead to the conclusion that glomerular endothelial dysfunction, and in particular damage to its glycocalyx, represents the most likely initiating step in diabetic microalbuminuria.
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Affiliation(s)
- S C Satchell
- Academic Renal Unit, University of Bristol, Southmead Hospital, Bristol, BS10 5NB, UK.
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164
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Chappell D, Jacob M, Rehm M, Stoeckelhuber M, Welsch U, Conzen P, Becker BF. Heparinase selectively sheds heparan sulphate from the endothelial glycocalyx. Biol Chem 2008; 389:79-82. [PMID: 18095872 DOI: 10.1515/bc.2008.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A healthy vascular endothelium is coated by the endothelial glycocalyx. Its main constituents are transmembrane syndecans and bound heparan sulphates. This structure maintains the physiological endothelial permeability barrier and prevents leukocyte and platelet adhesion, thereby mitigating inflammation and tissue oedema. Heparinase, a bacterial analogue to heparanase, is known to attack the glycocalyx. However, the exact extent and specificity of degradation is unresolved. We show by electron microscopy, immunohistological staining and quantitative measurements of the constituent parts, that heparinase selectively sheds heparan sulphate from the glycocalyx, but not the syndecans.
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Affiliation(s)
- Daniel Chappell
- Clinic of Anaesthesiology, Ludwig Maximilians University, Nussbaumstr. 20, D-80336 Munich
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165
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Abstract
The four dengue viruses are transmitted in tropical countries that circle the globe. All can cause syndromes that are self-limited or severe. The common severe syndrome--dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS)--is characterised by sudden vascular permeability generated by cytokines released when T cells attack dengue-infected cells. Dengue 1 virus became prevalent in Hawaii where it was transmitted by Aedes albopictus, producing a classic virgin soil epidemic, with clinical disease seen largely in adults. In Cuba and Singapore, sequential dengue infections at long intervals produced unusually severe disease in adults. Evidence suggests that enhancing and cross-reactive neutralising antibodies regulate dengue epidemics and disease severity. Classic DHF/DSS arises during initial dengue infections in infants with low circulating amounts of maternal dengue antibodies, an observation that precludes an exclusive causal role for secondary T-cell responses. Here, I review and discuss data on clinical diagnosis and pathophysiology of vascular permeability and coagulopathy, parenteral treatment of DHF/DSS, and new laboratory tests.
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Affiliation(s)
- Scott B Halstead
- Supportive Research and Development, Pediatric Dengue Vaccine Initiative, Internal Vaccine Institute, Seoul, South Korea.
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167
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Rehm M, Bruegger D, Christ F, Conzen P, Thiel M, Jacob M, Chappell D, Stoeckelhuber M, Welsch U, Reichart B, Peter K, Becker BF. Shedding of the Endothelial Glycocalyx in Patients Undergoing Major Vascular Surgery With Global and Regional Ischemia. Circulation 2007; 116:1896-906. [DOI: 10.1161/circulationaha.106.684852] [Citation(s) in RCA: 467] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Markus Rehm
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Dirk Bruegger
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Frank Christ
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Peter Conzen
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Manfred Thiel
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Matthias Jacob
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Daniel Chappell
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Mechthild Stoeckelhuber
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Ulrich Welsch
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Bruno Reichart
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Klaus Peter
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
| | - Bernhard F. Becker
- From the Clinic of Anesthesiology (M.R., D.B., F.C., P.C., M.T., M.J., D.C., K.P.), Department of Anatomy (M.S., U.W.), Clinic of Cardiac Surgery (B.R.), and Department of Physiology (B.F.B.), Ludwig-Maximilians-University, Munich, Germany
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Jacob M, Chappell D, Hofmann-Kiefer K, Conzen P, Peter K, Rehm M. Determinanten des insensiblen Flüssigkeitsverlustes. Anaesthesist 2007; 56:747-58, 760-4. [PMID: 17684711 DOI: 10.1007/s00101-007-1235-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Accurate perioperative fluid balance is the basis of a targeted infusion regimen. However, neither the initial status nor perioperative changes of the fluid compartments can be reliably measured in daily routine. In particular, insensible losses are not consistently assessed, so that substitution therapy is generally empirical. The object of this paper is to communicate the scientific data on this topic. Preoperative fasting (10 h) does not per se cause intravascular hypovolemia. In adults, total basal evaporation by way of the skin and airways and of any wounds during major abdominal interventions is usually less than 1 ml/kg/h. An inconstant fluid and protein shift towards the interstitial space perioperatively seems to be associated with hypervolemia, which suggests it should be preventable. The decisive factor in this context seems to be deterioration of the endothelial glycocalyx, whose further patho-physiological impact is currently only partially known. Clinical studies have revealed a link between fluid restriction and improved outcome after major abdominal surgery.
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Affiliation(s)
- M Jacob
- Klinik für Anaesthesiologie, Klinikum der Ludwig-Maximilians-Universität München Grosshadern-Innenstadt, Nussbaumstrasse 20, 80336 München.
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169
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Jacob M, Rehm M, Loetsch M, Paul JO, Bruegger D, Welsch U, Conzen P, Becker BF. The Endothelial Glycocalyx Prefers Albumin for Evoking Shear Stress-Induced, Nitric Oxide-Mediated Coronary Dilatation. J Vasc Res 2007; 44:435-43. [PMID: 17622736 DOI: 10.1159/000104871] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Accepted: 04/04/2007] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Shear stress induces coronary dilatation via production of nitric oxide (NO). This should involve the endothelial glycocalyx (EG). A greater effect was expected of albumin versus hydroxyethyl starch (HES) perfusion, because albumin seals coronary leaks more effectively than HES in an EG-dependent way. METHODS Isolated hearts (guinea pigs) were perfused at constant pressure with Krebs-Henseleit buffer augmented with 1/3 volume 5% human albumin or 6% HES (200/0.5 or 450/0.7). Coronary flow was also determined after EG digestion (heparinase) and with nitro-L-arginine (NO-L-Ag). RESULTS Coronary flow (9.50 +/- 1.09, 5.10 +/- 0.49, 4.87 +/- 1.19 and 4.15 +/- 0.09 ml/min/g for 'albumin', 'HES 200', 'HES 450' and 'control', respectively, n = 5-6) did not correlate with perfusate viscosity (0.83, 1.02, 1.24 and 0.77 cP, respectively). NO-L-Ag and heparinase diminished dilatation by albumin, but not additively. Alone NO-L-Ag suppressed coronary flow during infusion of HES 450. Electron microscopy revealed a coronary EG of 300 nm, reduced to 20 nm after heparinase. Cultured endothelial cells possessed an EG of 20 nm to begin with. CONCLUSIONS Albumin induces greater endothelial shear stress than HES, despite lower viscosity, provided the EG contains negative groups. HES 450 causes some NO-mediated dilatation via even a rudimentary EG. Cultured endothelial cells express only a rudimentary glycocalyx, limiting their usefulness as a model system.
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Affiliation(s)
- Matthias Jacob
- Clinic of Anesthesiology, Ludwig-Maximilians-University Munich, Munich, Germany.
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170
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Abstract
In recent decades, it has become evident that the endothelium is by no means a passive inner lining of blood vessels. This 'organ' with a large surface (approximately 350 m2) and a comparatively small total mass (approximately 110 g) is actively involved in vital functions of the cardiovascular system, including regulation of perfusion, fluid and solute exchange, haemostasis and coagulation, inflammatory responses, vasculogenesis and angiogenesis. The present chapter focusses on two central aspects of endothelial structure and function: (1) the heterogeneity in endothelial properties between species, organs, vessel classes and even within individual vessels and (2) the composition and role of the molecular layer on the luminal surface of endothelial cells. The endothelial lining of blood vessels in different organs differs with respect to morphology and permeability and is classified as 'continuous', 'fenestrated' or 'discontinuous'. Furthermore, the mediator release, antigen presentation or stress responses of endothelial cells vary between species, different organs and vessel classes. Finally there are relevant differences even between adjacent endothelial cells, with some cells exhibiting specific functional properties, e.g. as pacemaker cells for intercellular calcium signals. Organ-specific structural and functional properties of the endothelium are marked in the vascular beds of the lung and the brain. Pulmonary endothelium exhibits a high constitutive expression of adhesion molecules which may contribute to the margination of the large intravascular pool of leucocytes in the lung. Furthermore, the pulmonary microcirculation is less permeable to protein and water flux as compared to large pulmonary vessels. Endothelial cells of the blood-brain barrier exhibit a specialised phenotype with no fenestrations, extensive tight junctions and sparse pinocytotic vesicular transport. This barrier allows a strict control of exchange of solutes and circulating cells between the plasma and the interstitial space. It was observed that average haematocrit levels in muscle capillaries are much lower as compared to systemic haematocrit, and that flow resistance of microvascular beds is higher than expected from in vitro studies of blood rheology. This evidence stimulated the concept of a substantial layer on the luminal endothelial surface (endothelial surface layer, ESL) with a thickness in the range of 0.5-1 microm. In comparison, the typical thickness of the glycocalyx directly anchored in the endothelial plasma membrane, as seen in electron micrographs, amounts to only about 50-100 microm. Therefore it is assumed that additional components, e.g. adsorbed plasma proteins or hyaluronan, are essential in constituting the ESL. Functional consequences of the ESL presence are not yet sufficiently understood and acknowledged. However, it is evident that the thick endothelial surface layer significantly impacts haemodynamic conditions, mechanical stresses acting on red cells in microvessels, oxygen transport, vascular control, coagulation, inflammation and atherosclerosis.
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Affiliation(s)
- A R Pries
- Dept. of Physiology, Charité Berlin, Arnimallee 22, 14195 Berlin, Germany.
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172
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Reitsma S, Slaaf DW, Vink H, van Zandvoort MAMJ, oude Egbrink MGA. The endothelial glycocalyx: composition, functions, and visualization. Pflugers Arch 2007; 454:345-59. [PMID: 17256154 PMCID: PMC1915585 DOI: 10.1007/s00424-007-0212-8] [Citation(s) in RCA: 1197] [Impact Index Per Article: 70.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Accepted: 01/09/2007] [Indexed: 12/19/2022]
Abstract
This review aims at presenting state-of-the-art knowledge on the composition and functions of the endothelial glycocalyx. The endothelial glycocalyx is a network of membrane-bound proteoglycans and glycoproteins, covering the endothelium luminally. Both endothelium- and plasma-derived soluble molecules integrate into this mesh. Over the past decade, insight has been gained into the role of the glycocalyx in vascular physiology and pathology, including mechanotransduction, hemostasis, signaling, and blood cell–vessel wall interactions. The contribution of the glycocalyx to diabetes, ischemia/reperfusion, and atherosclerosis is also reviewed. Experimental data from the micro- and macrocirculation alludes at a vasculoprotective role for the glycocalyx. Assessing this possible role of the endothelial glycocalyx requires reliable visualization of this delicate layer, which is a great challenge. An overview is given of the various ways in which the endothelial glycocalyx has been visualized up to now, including first data from two-photon microscopic imaging.
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Affiliation(s)
- Sietze Reitsma
- Department of Biophysics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - Dick W. Slaaf
- Department of Biophysics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
- Department of Biomedical Engineering, Technische Universiteit Eindhoven, Eindhoven, The Netherlands
| | - Hans Vink
- Department of Physiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Marc A. M. J. van Zandvoort
- Department of Biophysics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - Mirjam G. A. oude Egbrink
- Department of Physiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
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Jacob M, Conzen P, Finsterer U, Krafft A, Becker BF, Rehm M. Technical and physiological background of plasma volume measurement with indocyanine green: a clarification of misunderstandings. J Appl Physiol (1985) 2006; 102:1235-42. [PMID: 17110515 DOI: 10.1152/japplphysiol.00740.2006] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The indocyanine green (ICG) dilution technique (DT) is frequently used for plasma volume (PV) measurement. However, because of inadequate knowledge about the properties of this dye, lack of accuracy has been attributed to the method. The aim of this report is to provide physiological background information about the ICG-DT to avoid some profound misunderstandings. When performing tracer dilution, one has to consider the tracer's distribution space before interpreting the result. For ICG, the distribution space is the total PV, i.e., circulating + noncirculating PV, fixed within the endothelial glycocalyx. The distribution space of red blood cells and large molecules, in contrast, is only the circulating part of PV. Therefore, it is erroneous to compare directly PV derived from different tracer dilution methods. The transcapillary escape rate of ICG should not relevantly influence measured PV if the method is performed properly, i.e., if a short time window of measurement is subjected to monoexponential extrapolation. A major problem of PV measurement in general is that the target itself is very inconstant. Thus, checking for constancy of ICG-DT with two consecutive measurements is unreliable. Nevertheless, the ICG-DT is a useful tool for determining PV, provided it is well understood by the investigator to enable correct interpretation of the results.
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Affiliation(s)
- Matthias Jacob
- Klinik für Anästhesiologie, Ludwig-Maximilians-Universität München, Nussbaumstr. 20, D-80336 Munich, Germany.
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174
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Affiliation(s)
- M Jacob
- Klinik für Anästhesiologie, Ludwig-Maximilians-Universität, München, Germany
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175
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Tatara T, Tashiro C. Analysis using a linear viscoelastic model of the in vitro osmotic kinetics of polydisperse synthetic colloids. Biomacromolecules 2006; 6:1732-8. [PMID: 15877400 DOI: 10.1021/bm0500143] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study clarifies the contribution to overall osmotic kinetics of colloid osmotic pressure (Pi) and the interaction of synthetic colloids with the membrane. Solutions (6%) of dextran with weight average molecular weight (MW(w)) 68 800 (DEX 70), dextran with MW(w) 40 000 (DEX 40), hydroxyethyl starch with MW(w) 70 000 (HES 70), gelatin with MW(w) 60 000 and albumin were tested. An osmotic flow cell fitted with membranes of molecular weight cutoff size 30 000 or 50 000 was used to measure time-dependent changes in Pi for each of these solutions. A linear viscoelastic model was fitted to the curve describing changes to Pi as a function of time. Values of total effective Pi for DEX 40 and DEX 70 were larger than those for HES 70, gelatin, and albumin. As an index of solute-solvent exchange rate at the membrane surface, these values were in the order DEX 40 > DEX 70, HES 70 > gelatin, albumin. The findings suggest that DEX 40 may be preferable for the temporary restoration of plasma volume because of a heightened initial osmotic force. In contrast, the osmotic force exerted by gelatin is slower to increase but is likely to be longer lasting in vivo as a result of the inhibition of gelatin from penetrating the capillary membrane due to its interaction with negatively charged groups in the endothelial glycocalyx.
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Affiliation(s)
- Tsuneo Tatara
- Department of Anesthesiology, Hyogo College of Medicine, Hyogo 663-8501, Japan.
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176
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Gonscherowski V, Becker BF, Moroder L, Motrescu E, Gil-Parrado S, Gloe T, Keller M, Zahler S. Calpains: a physiological regulator of the endothelial barrier? Am J Physiol Heart Circ Physiol 2005; 290:H2035-42. [PMID: 16373586 DOI: 10.1152/ajpheart.00772.2004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The intracellular protease calpain, abundant in endothelial cells (EC), is assumed to be inactive under physiological conditions but may account for Ca2+ -linked pathophysiological events. However, nonstimulated EC contained autolyzed, activated calpain. Adding 12-48 microM calpain inhibitor I (CI) or 0.5-1 microM of the novel, membrane-permeable conjugate of calpastatin peptide-penetratin (CPP) caused rapid rounding and retraction of cultured EC (phase contrast, capacitance) and translocation of Syk, Rac, and Rho to the membrane, signifying activation upon inhibition of calpain. Isolated hearts (guinea pig) perfused with 12 microM CI or 0.5 muM CPP developed coronary leak. We conclude that calpain is constitutively active in EC and regulates vascular permeability by governing cell-cell attachment.
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177
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Bruegger D, Jacob M, Rehm M, Loetsch M, Welsch U, Conzen P, Becker BF. Atrial natriuretic peptide induces shedding of endothelial glycocalyx in coronary vascular bed of guinea pig hearts. Am J Physiol Heart Circ Physiol 2005; 289:H1993-9. [PMID: 15964925 DOI: 10.1152/ajpheart.00218.2005] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Atrial natriuretic peptide (ANP) is reported to enhance vascular permeability in vivo. Our aim was to evaluate the impact of ANP on coronary extravasation of fluids and macromolecules and on the integrity of the endothelial glycocalyx. Isolated guinea pig hearts ( n = 6/group) were perfused with Krebs-Henseleit buffer in a Langendorff mode. A 6% hydroxyethyl starch (HES) solution was infused into the coronary system for 20 min without (Control group) and simultaneously with (ANP group) ANP at 10−9 M. In two further series, the glycocalyx was enzymatically degraded by means of heparinase (Hep) application (10 IU over 15 min), followed again by the infusion of HES in the absence (Hep group) and presence (ANP+Hep group) of ANP. Net fluid filtration, extravasation of HES, electron microscopic visualization of the glycocalyx, and quantification of shedding of syndecan-1, a component of the glycocalyx, were determined. An increase in fluid leak was observed in ANP, ANP+Hep, and Hep hearts [+29%, +31%, +14%, respectively; a decrease was observed in Control hearts (−13%)]. Similarly, an accelerated extravasation of colloid was observed in these three groups. Coronary release of syndecan-1 increased 9- to 18-fold during infusion of ANP. Electron microscopy revealed a dramatic degradation of the glycocalyx after ANP. These results indicate that the endothelial glycocalyx serves as a barrier to transmural exchange of fluid and colloid in the coronary vascular system. ANP causes rapid shedding of individual components of the glycocalyx and histologically detectable degradation. Thus the permeability-increasing effect of ANP may be at least partially related to changes in the integrity of the endothelial glycocalyx.
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Affiliation(s)
- Dirk Bruegger
- Clinic for Anesthesiology, Ludwig-Maximilians-Univ., Marchioninistr. 15, D-81377 Munich, Germany
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178
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Dynamic purine signaling and metabolism during neutrophil-endothelial interactions. Purinergic Signal 2005; 1:229-39. [PMID: 18404508 PMCID: PMC2096542 DOI: 10.1007/s11302-005-6323-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 03/07/2005] [Accepted: 03/23/2005] [Indexed: 01/09/2023] Open
Abstract
During episodes of hypoxia and inflammation, polymorphonuclear leukocytes (PMN) move into underlying tissues by initially passing between endothelial cells that line the inner surface of blood vessels (transendothelial migration, TEM). TEM creates the potential for disturbances in vascular barrier and concomitant loss of extravascular fluid and resultant edema. Recent studies have demonstrated a crucial role for nucleotide metabolism and nucleoside signaling during inflammation. These studies have implicated multiple adenine nucleotides as endogenous tissue protective mechanisms invivo. Here, we review the functional components of vascular barrier, identify strategies for increasing nucleotide generation and nucleoside signaling, and discuss potential therapeutic targets to regulate the vascular barrier during inflammation.
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