[The role of vitamin E during pregnancy--anti-platelet aggregation activity of alpha-tocopherol]

To clarify the role of vitamin E (alpha-tocopherol) during pregnancy, we mainly investigated the relation between platelet function and vitamin E and obtained the following results. 1. The concentration of vitamin E (alpha-tocopherol) in plasma and platelet increased gradually during pregnancy. The concentration of vitamin E in plasma was 6.65 micrograms/ml in non pregnant women and 15.5 micrograms/ml in full term pregnant women. And the concentration of vitamin E in platelet was 99 micrograms/g protein in non pregnant women and 244 micrograms/g protein in full term pregnant women. 2. Vitamin E (alpha-tocopherol) inhibited platelet aggregation induced by ADP (adenosine diphosphate) and PAF(platelet activating factor). At a concentration of 500 micrograms/ml vitamin E almost completely inhibited platelet aggregation induced by ADP and PAF. 3. There exists a strong platelet aggregation inhibiting activity in human placental brush border membrane vesicles. At a protein concentration of 20 micrograms/ml the brush border membrane vesicles almost completely inhibited platelet aggregation induced by ADP and PAF. 4. With the co-existence of the brush border membrane vesicles, the platelet aggregation inhibiting activity of vitamin E (alpha-tocopherol) increased prominently. These results indicate that vitamin E plays an important role in the regulation of platelet function and might contribute to the maintenance of placental microcirculation by inhibiting platelet aggregation.