Plasma alpha-tocopherol and coronary endothelium-dependent vasodilator function

Background-In the presence of atherosclerosis, the coronary endothelial vas omotor response to acetylcholine is frequently abnormal but is variable bet ween patients. We tested the hypothesis that the plasma concentration of al pha-tocopherol is associated with the preservation of nitric oxide-mediated endothelium-dependent vasomotion. Methods and Results-We studied 15 men and 6 women (mean age 61+/-10 years) at coronary angiography who were not taking vitamin supplements. Coronary e ndothelium-dependent and -independent vasomotion was assessed by intracoron ary infusions of acetylcholine and nitroglycerin. The vasomotor responses w ere compared with the plasma concentration of alpha-tocopherol and the plas ma alpha-tocopherol concentration relative to total lipid (total cholestero l plus triglycerides). The mean plasma alpha-tocopherol was 25.6+/-6.1 mu m ol/L, total cholesterol 193+/-27 mg/dL, triglycerides 115+/-66 mg/dL, and a lpha-tocopherol to total lipid 4.2+/-0.9 mu mol . L-1 . (mmol/L)(-1). The m ean vasomotor response to acetylcholine was -1% (range -33% to 28%) and to nitroglycerin 22% (range 0% to 54%). Plasma alpha-tocopherol was significan tly correlated with the acetylcholine response (r=0.49, P<0.05) but not the nitroglycerin response (r=0.13, P>0.05). The acetylcholine response remain ed significant after adjustment for other potential sources of oxidant stre ss (total cholesterol, diabetes mellitus, smoking, angina class) (P<0.01). The relative concentration of alpha-tocopherol to total lipid was not relat ed to endothelial function (r=0.24, P=0.3, n=20). Conclusions-alpha-Tocopherol may preserve endothelial vasomotor function in patients with coronary atherosclerosis. This effect may be related primari ly to the action of alpha-tocopherol in the vascular wall. Further studies that assess the impact of alpha-tocopherol supplementation as therapy of en dothelial dysfunction are justified.