Systemic adenosine‐induced impairment of endothelial glycocalyx barrier properties is associated with a reduction in functional capillary density in hindlimb skeletal muscle of rats

Abstract

ObjectiveTo determine the effect of systemic adenosine infusion on dextran accessibility in capillaries of rat skeletal muscle.MethodsA bolus of fluorescently‐labeled small (40 kDa) dextrans (Dex40) and large (2000 kDa) dextrans (Dex2000) was i.v. infused in anesthetized rats. This was done in control rats (N=4) and in rats that received continuous adenosine infusion (2 mg/ml; 1.5 ml/h) (N=3) for 15 minutes. 3 minutes after dextran infusion, calf muscles were removed and sectioned. Images were captured using fluorescence microscopy. For both tracers, the number as well as the diameter of tracer‐filled capillaries was determined.ResultsIn control rats the diameter of Dex2000 filling in capillaries was smaller compared to Dex40, 3.27 ± 0.05 μm versus 3.48 ± 0.08 μm (MEAN ± SEM). During adenosine infusion, diameters for both tracers did not differ anymore, 3.24 ± 0.24 (Dex40) versus 3.34 ± 0.27 μm (Dex2000). The number of dextran perfused capillaries in control animals was smaller for Dex2000 than for Dex40, 357 ± 31 versus 658 ± 51 and decreased more for Dex2000 (270 ± 22, P<0.05) than for Dex40 (572 ± 60, NS) during adenosine infusion.ConclusionGlycocalyx recruitment during systemic adenosine infusion in rats is associated with a decrease in vascular anatomic volume in resting hindlimb muscle.Sponsored by Dutch Heart Foundation (NHS2009B56)