Arteriogenesis: role of nitric oxide.

Arteriogenesis is an important process for adapting the pre-existing circuit of vessels into functional collateral conduits for delivery of oxygen enriched blood to tissue distal to occlusion of a large, peripheral conduit artery. Recent evidence has shown that arteriogenesis is regulated by nitric oxide (NO), angiogenic factors and shear stress. NO significantly impacts vasomotor tone to enhance conductance of the newly recruited collateral arteries, and this effect is augmented by exercise training prior to arterial occlusion. NO-mediated increases in vascular conductance allows for greater collateral dependent blood flow to the tissue distal to occlusion. NO production is also critical to the efficacy of therapeutic arteriogenesis achieved by delivery of exogenous angiogenic growth factors (VEGF, FGF-2) or by exercise training. The critical role of NO in therapeutic arteriogenesis is independent of NO-mediated changes in vascular conductance and implies a central role in arteriogenic signaling events. Maintenance, or improvement, of NO production and signaling, such as with regular exercise, may improve endothelial cell function and thus may help preserve the arteriogenic potential of preexisting collateral networks.