MODULATION BY DIETARY VITAMIN-E AND SELENIUM OF CLOTTING WHOLE-BLOOD THROMBOXANE-A2 AND AORTIC PROSTACYCLIN SYNTHESIS IN RATS

The effect of dietary vitamin E and selenium (Se) on aortic prostacycl in (PGI2) and clotting whole blood thromboxane (TX) A2 synthesis in 1- month-old Fischer 344 rats was investigated. Rats were fed basal semi- purified diets deficient in vitamin E and Se or basal diet supplemente d with either 200 IU vitamin E and/or 0.2 ppm Se per kg diet for 2 mon ths. Ex vivo production of TXB2 and 6-keto-PGF1alpha, the correspondin g stable metabolites of TXA2 and PGI2, were measured in whole blood an d aortic rings, respectively. Animals fed vitamin E-deficient diet had significantly (P < 0.05) lower plasma levels of alpha-tocopherol than those fed vitamin E-supplemented diet. Plasma Se was undetected and a ctivity of plasma glutathione peroxidase was diminished in rats fed Se -deficient diets. Vitamin E and Se treatments affected TXA2 and PGI2 p roduction differently. Aortic PGI2 synthesis was affected by both diet ary vitamin E and Se, whereas whole blood TXA2 synthesis was only affe cted by dietary vitamin E. These results suggest that vitamin E and Se have specific and different effects on TXA2 and PGI2 synthesis, and t hat their combined supplementation may have a favorable effect on PGI2 :TXA2 ratio.