Acute attenuation of glycocalyx barrier properties increases coronary blood volume independently of coronary flow reserve

• Published in: American journal of physiology. Heart and circulatory physiology 2010-02, Vol.298 (2), p.H515-H523
• Main Authors: Brands, Judith, Spaan, Jos A. E, Van den Berg, Bernard M, Vink, Hans, VanTeeffelen, Jurgen W. G. E
• Format: Article
• Language: English
• Subjects: Adenosine; Adenosine - pharmacology; Animals; Blood Volume - physiology; Cell Membrane - physiology; Coronary vessels; Coronary Vessels - drug effects; Coronary Vessels - physiology; Enzymes; Erythrocytes; Female; Glycocalyx - drug effects; Glycocalyx - physiology; Goats; Hyaluronoglucosaminidase - pharmacology; Models, Animal; Models, Biological; Regional Blood Flow - physiology; Studies; Vasodilation - drug effects; Vasodilator Agents - pharmacology
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.01306.2008

1 Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht; and Departments of 2 Medical Physics and 3 Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands Submitted December 18, 2008 ; accepted in final form November 23, 2009 Vascular endothelium is covered with an extensive mesh of glycocalyx constituents, which acts like an effective barrier up to several micrometers thick that shields the luminal surface of the vasculature from direct exposure to flowing blood. Many studies report that various enzymatic and pharmaceutical challenges are able to increase glycocalyx porosity, resulting in farther permeation of plasma macromolecules and greater access of red blood cells into glycocalyx domain. Attenuation of glycocalyx barrier properties therefore potentially increases the amount of blood that effectively occupies available microvascular volume. We tested in the present study whether attenuation of coronary glycocalyx barrier properties actually increases coronary blood volume and whether such changes would be noticeable during measurements of coronary flow reserve using adenosine. In anesthetized goats ( n = 6) with cannulated left main coronary artery that were perfused under controlled pressure, coronary blood volume was measured via the indicator-dilution technique using high-molecular-weight (2,000 kDa) dextrans as plasma tracer and labeled red blood cells as red blood cell tracer. Coronary blood volume was determined at baseline and during intracoronary infusion of adenosine causing maximal vasodilation (0.2–0.6 mg·kg –1 ·h –1 ) before and after intracoronary hyaluronidase treatment (170,000 units) of the glycocalyx. With an intact glycocalyx, coronary blood volume was 18.9 ± 1.1 ml/100 g heart tissue at baseline, which increased to 26.3 ± 2.7 ml/100 g after hyaluronidase treatment of the coronary glycocalyx. Maximal vasodilation by administration of adenosine further increased coronary blood volume to 33.9 ± 6.8 ml/100 g, a value not different from the maximal coronary blood volume of 33.2 ± 5.3 ml/100 g obtained by administration of adenosine in the absence of hyaluronidase treatment. Adenosine-induced increases in coronary conductance were not affected by hyaluronidase treatment. We conclude that acute attenuation of glycocalyx barrier properties increases coronary blood volume by 40%, which is of similar magnitude as additional changes in coronary blood v