Relationships between endothelium-dependent vasodilation, serum vitamin E and plasma isoprostane 8-iso-PGF(2 alpha) levels in healthy subjects

Due to the reported associations between a low intake of vitamin E and athe rosclerosis on one hand, and between endothelial dysfunction and atheroscle rosis on the other hand, we investigated the relationship between endotheli um-dependent vasodilation and serum levels of vitamin E (alpha- and gamma-t ocopherol) as well as the lipid peroxidation markers malondialdehyde and 8- iso-PGF(2 alpha) in a healthy population. Healthy subjects (31 men and 25 w omen), aged between 20 and 69 years, underwent measurements of forearm bloo d flow (FBF) at rest and during local infusion of 2 and 4 mu g/min of metha choline (Mch, to evaluate endothelium-dependent vasodilation) and 5 and 10 mu g/min of sodium nitroprusside (SNP, to evaluate endothelium-independent vasodilation, and during reactive hyperemia using venous occlusion plethysm ography. Serum cl-tocopherol concentration was significantly related to the index of endothelial function (r = 0.46, p < 0.01), defined as the ratio b etween the maximal dilatations during Mch and SNP infusions. Serum gamma-to copherol levels were positively related to the maximal FBF during reactive hyperemia (r = 0.54, p < 0.01) in women only. Furthermore, in women only, p lasma 8-iso-PGF(2 alpha) levels were inversely related to the relative incr eases in FBF during both Mch and SNP infusions (r = -0.58 and r = -0.59, p < 0.01 for both). The results show a relationship between the levels of alp ha-tocopherol and endothelial vasodilatory function, suggesting a beneficia l role for this potent lipid-soluble antioxidant also in a population sampl e of apparently healthy subjects. Furthermore, in women, the accumulation o f lipid peroxidation products such as 8-iso-PGF(2 alpha) seems to be associ ated with an impaired vasodilation in general. Copyright(C) 1999 S. Karger AG. Basel.