Abstract
There currently is great interest in translating findings about the importance of nitric oxide (NO) in vascular biology to the clinical arena. The bioactivity of endothelium-derived NO can readily be assessed in human subjects as vasodilation of conduit arteries or increased flow, which reflects vasodilation of resistance vessels. This chapter provides an update on the available noninvasive methodology to assess endothelium-dependent vasodilation in human subjects.