1.Vitamin E administration improves endothelial function in hypercholesterolaemic animals but, generally, has not been found to do so in man. The aim of this study was to determine whether vitamin E administration improves basal or stimulated function of the nitric oxide (·NO) dilator system in patients with hypercholesterolaemia.
2.Seven subjects aged 47±3 (±S.E.M.) years with moderately elevated serum cholesterol concentrations (6.0±0.1 ;mmol/l) were given 4 weeks of placebo therapy followed by 500 i.u. of vitamin E twice daily for 4 weeks. Endothelium-dependent and -independent vasodilatation were assessed by intrabrachial infusion of acetylcholine and sodium nitroprusside, and forearm blood flow was measured by strain-gauge plethysmography. Basal ·NO function was assessed by infusion of NG-monomethyl-l-arginine.
3.Plasma α-tocopherol concentration was enhanced after administration of vitamin E (34.6±1.8 to 86.9±9.6 ;μmol/l; P< 0.001). In addition, vitamin E administration significantly increased acetylcholine-mediated vasodilatation whether the results were expressed in terms of changes in absolute forearm blood flow (P< 0.01), forearm vascular resistance (P< 0.05) or forearm blood flow ratios (P< 0.001). Similarly, absolute forearm blood flow (P< 0.05), forearm vascular resistance (P< 0.01) and forearm blood flow ratio (P< 0.01) responses to NG-monomethyl-l-arginine were augmented by vitamin E therapy. Sodium nitroprusside responses were unaltered.
4.These results indicate that 4 weeks therapy with 1000 i.u. of vitamin E daily improves basal and stimulated ·NO-related endothelial function in subjects with hypercholesterolaemia.