Modulation of Pre-Capillary Arteriolar Pressure with Drag-Reducing Polymers: A Novel Method for Enhancing Microvascular Perfusion

Objective: We have shown that drag-reducing polymers (DRP) enhance capillary perfusion during severe coronary stenosis and increase red blood cell velocity in capillaries, through uncertain mechanisms. We hypothesize that DRP decreases pressure loss from the aorta to the arteriolar compartment. Methods: Intravital microscopy of the rat cremaster muscle and measurement of pressure in arterioles (diameters 20-132μm) was performed in 24 rats. DRP (polyethylene oxide, 1ppm) was infused i.v. and measurements were made at baseline and 20minutes after completion of DRP infusion. In a 10-rat subset, additional measurements were made three minutes after the start, and one to five and 10minutes after completion of DRP. Results: Twenty minutes after the completion of DRP, mean arteriolar pressure was 22% higher than baseline (from 42±3 to 49±3mmHg, p<0.005, n=24). DRP decreased the pressure loss from the aorta to the arterioles by 24% (from 35±6 to 27±5mmHg, p=0.001, n=10). In addition, there was a strong trend toward an increase in pressure at 10minutes after the completion of DRP (n=10). Conclusions: Drag-reducing polymers diminish pressure loss between the aorta and the arterioles. This results in a higher pre-capillary pressure and probably explains the observed DRP enhancement in capillary perfusion.