LACK OF EFFECT OF VITAMIN-E ON L-ARGININE-RESPONSIVE ENDOTHELIAL DYSFUNCTION IN PATIENTS WITH MILD HYPERCHOLESTEROLEMIA AND CORONARY-ARTERYDISEASE

1. Dietary supplementation with vitamin E reduces ischaemic events in patients with established coronary artery disease and improves endothe lial function in cholesterol-fed rabbits, We examined whether such die tary supplementation with vitamin E improves endothelial function in p atients with mild hypercholesterolaemia and coronary artery disease, 2 . Twenty patients (total cholesterol 6.8 +/- 1.1 mmol/l, mean+/-SD) wi th angiographically documented coronary artery disease were randomly a llocated to receive placebo (n = 10) or vitamin E 400 i.u, daily, (n=1 0) for 8 weeks. Endothelium-dependent and independent vasodilatation w ithin forearm vasculature was assessed by brachial artery infusion of acetylcholine (co-infused with saline vehicle and L-arginine) and nitr oprusside before and after supplementation. 3. Plasma concentrations o f vitamin E increased from 32.9 +/- 3.8 to 69.1 +/- 11.8 mu mol/l (mea ns +/- SE) in the vitamin E-supplemented group (P < 0.01) but did not change significantly in the placebo group, Lipid profiles remained sim ilar before and after supplementation in both groups, Forearm blood ho w responses to acetylcholine (7.5 and 15 mu g/min) and nitroprusside ( 3 and 10 mu g/min) were similar before and after supplementation in bo th groups, Acute intra-arterial administration of L-arginine (10 mg/mi n) augmented the response to acetylcholine (15 mu g/min) in both group s before and after supplementation to a similar degree (mean augmentat ion: 60 +/- 18%, P < 0.01). 4. Acute administration of L-arginine reve rses endothelial dysfunction in forearm vasculature of patients with m ild hypercholesterolaemia and coronary artery disease but supplementat ion with vitamin E (400 i.u. daily) for 8 weeks does not reverse L-arg inine-responsive endothelial dysfunction.