Effect of Red Blood Cell Aggregation on Arteriolar Cell-Free Layer Formation and its Physiological Functions

Abstract

This thesis examined the effect of erythrocyte aggregation on cell-free layer formation in small arterioles, with emphasis on how the layer variations could modulate nitric oxide bioavailability (NO) and vascular tone. A new computer based method was developed to overcome a potential overestimation problem of the cell-free layer width. The mean and temporal variability of the layer width were enhanced by aggregation under reduced flow conditions. Blood flow partitioning at an arteriolar bifurcation resulted in spatial variations of the layer formation in the arterioles. Aggregation promoted symmetry recovery of the layer widths on opposite sides of downstream arterioles but increased tendency of the layer formation in smaller downstream arterioles. NO bioavailability in arterioles was improved by the layer variations, which was mediated by concomitant changes in wall shear stress (WSS) and endothelial NO production. This effect was enhanced by aggregation, resulting in augmentation of sGC activation, in turn promoting vasodilation.