Heterogenous Nature of Flow-Mediated Dilatation in Human Conduit Arteries In Vivo: Relevance to Endothelial Dysfunction in Hypercholesterolemia

ABSTRACT —Flow-mediated dilatation (FMD) of conduit arteries is dependent on an intact endothelium, although the mechanisms are not fully understood. Using high-resolution ultrasound, we examined the role of endothelial mediators in radial artery dilatation in response to transient (short period of reactive hyperemia) and sustained (prolonged period of reactive hyperemia, hand warming, or an incremental infusion of acetylcholine into the distal radial artery) hyperemia. After short episodes of reactive hyperemia, FMD was abolished by local infusion of the nitric oxide synthesis inhibitor Nmonomethyl-l-arginine (5.3±1.2% versus 0.7±0.7%, P