Figure 1.

Schematic representation of the relative contribution of the 3 major endothelial- derived vasodilating factors. The vasodilatory contribution of nitric oxide (green) is largest in large calibre vessels such as conduit arteries, decreasing with vessel size. The opposite is observed for EDHF (yellow). Its vasodilatory role is most pronounced in small calibre vessels such as arterioles, this contribution to vessel relaxation decreases as vessel size increases. Whether the influence of prostacyclin (blue) is dependent on vessel size is less established, though it is expressed in both large and small vessels. The influence of contribution of prostacyclin in the adult is much smaller than that of NO and EDHF.