Effects of adenosine on systemic glycocalyx volume in goats

Abstract

It has been suggested that adenosine increases perfused capillary volume by reducing the effective dimension of a blood excluding intravascular glycocalyx compartment (Klitzman 1979; VanTeeffelen 2005). In the present study, the effect of adenosine on systemic glycocalyx volume was assessed in goats by comparing the intravascular distribution volumes (Vd) of labeled red blood cells (RBCs, glycocalyx impermeable tracer) and neutral Dextran 40 (MW 40 kDa, glycocalyx permeable tracer). In open-chest anesthetized goats (n=6), Dextran 40 and RBCs were simultaneously infused via the vena femoralis. Plasma Vd was calculated from the steady-state dilution of RBCs and systemic hematocrit, and was 29.5 ± 2.1 (SEM) and 36.8 ± 2.2 ml/kg BW in control and during adenosine, respectively (P=0.05). Vd of dextran 40 was derived from its estimated plasma concentration at t = 30 s after injection and was 55.1 ± 5.6 and 38.7 ± 3.7 ml/kg in control and during adenosine (P<0.001). Systemic glycocalyx volume was 25.6 ± 1.9 and 1.9 ± 3.5 ml/kg in control and during adenosine (P<0.01). It is concluded that adenosine reduces systemic glycocalyx volume. This finding supports the concept that dynamic modulation of glycocalyx volume by adenosine may contribute to local control of organ blood flow by lowering microvascular resistance and enhancing capillary exchange capacity. Support by NHF (2003B181 to JB), NWO (902-16-192 to JT), and KNAW (HV).