Hyaluronidase treatment of the endothelial glycocalyx impairs adenosine mediated recruitment of coronary volume

Abstract

It is hypothesized that coronary hyperemia by adenosine is accompanied by increased access for blood to the endothelial glycocalyx (EG) (VanTeeffelen, 2005). In the present study, the effect of glycocalyx degradation by hyaluronidase on adenosine mediated volume recruitment was assessed in goats. Labelled red blood cells (RBC) were infused as a bolus in the left main coronary artery in open‐chest anesthetized goats using a perfusion system. Blood samples were collected from the great cardiac vein every 0.5–1 second. Coronary red blood cell volume (Vcor) was calculated by multiplying mean RBC transit time with simultaneously measured coronary RBC flow. This measurement was done in control (con) and during adenosine (ado), before as well as after hyaluronidase treatment. Adenosine‐induced coronary volume recruitment (Vcor,ado/Vcor,con) and flow reserve (Qado/Qcon) were calculated; in control Vcor,ado/Vcor,con was 2.14 ± 0.7 and Qado/Qcon was 2.25 ± 0.8. After hyaluronidase Vcor,ado/Vcor,con reduced to 1.87 ± 0.8 (P<0.05), while Qado/Qcon was not affected (2.22 ± 0.8, N.S. compared to before hyaluronidase). These data demonstrate that enzymatic degradation of the coronary EG impairs the ability of adenosine to recruit coronary vascular volume. It is concluded that recruitment of EG volume contributes to optimal matching of hyperemic coronary flow and volume. Supported by NHF grants 2005T037 and 2003B181.