The role of nitric oxide in endothelium-dependent vasodilation of hypercholesterolemic patients.

BACKGROUNDPatients with hypercholesterolemia have a reduced response to endothelium-dependent vasodilators. However, the regulatory function of the endothelium on vascular tone is mediated through the release of several vasoactive substances; therefore, a reduced response to endothelium-dependent agents does not identify which of the factors released by the endothelium is involved in this abnormality.METHODS AND RESULTSTo investigate the role of nitric oxide in the endothelium-dependent vasodilation in hypercholesterolemia, we studied the effect of NG-monomethyl-L-arginine (L-NMMA), an inhibitor of endothelial nitric oxide synthesis, on basal vascular tone and on the responses to acetylcholine, an endothelium-dependent vasodilator, and to sodium nitroprusside, a direct smooth muscle dilator. The study included 33 hypercholesterolemic patients (17 men; 51 +/- 8 years; plasma cholesterol, > or = 240 mg/dL) and 23 normal controls (12 men; 48 +/- 7 years; plasma cholesterol, < 210 mg/dL). Drugs were infused i...