Fig. (2).

Pressure gradient of a developing collateral. Early after the development of arterial stenosis, low pressure distal to the stenosis draws flow through the collateral and increases shear stress on the endothelium (A). Collateral development reaches a plateau; collateral diameter increases, reducing collateral shear stress (B). An increase in donor artery pressure during exercise training reintroduces a pressure gradient across the collateral; fluid shear stress again increases across the collateral endothelium (C). (A higher resolution / colour version of this figure is available in the electronic copy of the article).