Beneficial effect of vitamin E administration on nitric oxide function in subjects with hypercholesterolaemia.
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 alpha-tocopherol concentration was enhanced after administration of vitamin E (34.6+/-1.8 to 86.9+/-9.6 micromol/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.
Green
D
D
Department of Human Movement Studies, The University of Western Australia, Nedlands, Western Australia 6907, Australia.
O'Driscoll
G
G
Rankin
J M
JM
Maiorana
A J
AJ
Taylor
R R
RR
D000109:Acetylcholine; D004334:Drug Administration Schedule; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D005260:Female; D005542:Forearm / Q000098:blood supply; D006801:Humans; D006937:Hypercholesterolemia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside; D012039:Regional Blood Flow / Q000187:drug effects; D016037:Single-Blind Method; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents; D014810:Vitamin E / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D019323:omega-N-Methylarginine
D014665:Vasodilator Agents; D014810:Vitamin E; D009599:Nitroprusside; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D000109:Acetylcholine