Enzymatic endothelial glycocalyx degradation increases arterial‐venous oxygen exchange in the heart

A relatively thick endothelial glycocalyx forms the true interface between blood and the vascular wall, and thereby limits microvascular volume available for perfusion and exchange. In previous studies we have shown that hyaluronidase treatment increases coronary microvascular blood volume. We now hypothesize that acute functional or enzymatic reduction of glycocalyx volume increases microvascular exchange capacity. In the current study the effect of enzymatic glycocalyx degradation on myocardial oxygen exchange was assessed in goats (n=5). Blood samples were collected simultaneously from great cardiac vein and aorta, and blood flow was measured in the LAD. The measurement was done in control and after hyaluronidase treatment. Hyaluronidase treatment increased arterial‐venous oxygen difference significantly from 7.0 ± 0.2 to 8.3 ± 0.3 ml/100ml, which was associated with a reduced coronary flow from 66.5 ± 9.1 to 46.4 ± 2.9 ml/min/100gr tissue (P<0.05). Rate‐pressure product and oxygen consumption remained unaltered. In conclusion, acute enzymatic degradation of glycocalyx volume increases arterial‐venous oxygen exchange, consistent with our previous finding on the effect of hyaluronidase treatment on microvascular blood volume. Supported by NHF grants 2005T037 and 2003B181.