Plasma α-Tocopherol and Coronary Endothelium-Dependent Vasodilator Function

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Abstract
Background —In the presence of atherosclerosis, the coronary endothelial vasomotor response to acetylcholine is frequently abnormal but is variable between patients. We tested the hypothesis that the plasma concentration of α-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 endothelium-dependent and -independent vasomotion was assessed by intracoronary infusions of acetylcholine and nitroglycerin. The vasomotor responses were compared with the plasma concentration of α-tocopherol and the plasma α-tocopherol concentration relative to total lipid (total cholesterol plus triglycerides). The mean plasma α-tocopherol was 25.6±6.1 μmol/L, total cholesterol 193±27 mg/dL, triglycerides 115±66 mg/dL, and α-tocopherol to total lipid 4.2±0.9 μmol · L −1 · (mmol/L) −1 . The mean vasomotor response to acetylcholine was −1% (range −33% to 28%) and to nitroglycerin 22% (range 0% to 54%). Plasma α-tocopherol was significantly correlated with the acetylcholine response ( r =0.49, P 0.05). The acetylcholine response remained significant after adjustment for other potential sources of oxidant stress (total cholesterol, diabetes mellitus, smoking, angina class) ( P r =0.24, P =0.3, n=20). Conclusions —α-Tocopherol may preserve endothelial vasomotor function in patients with coronary atherosclerosis. This effect may be related primarily to the action of α-tocopherol in the vascular wall. Further studies that assess the impact of α-tocopherol supplementation as therapy of endothelial dysfunction are justified.