Platelet Aggregation Inhibition Activity of Placental Brush Border Membrane

Abstract

Thrombus occurs frequently in the placental chorionic lumen of patients with Pre-ecclampsia (EPH) gestosis, and participation of platelets is suggested in the pathology of the diseases. In the placental tissues, there is an antiplatelet aggregating factor which plays an important role in the maintenance of microcirculation in the placenta. The brush border membrane of the placental chorioepithe-lium plays the part of the vasoendothelium as it is the point of direct contact with the maternal blood flow in the chorionic lumen. It has already been confirmed that a strong inhibitory action on platelet aggregation is present in the vasoendothelium, and its main active mechanism is shown to be prostacyclin (PG I₂) and ADP degrading by an ADPase-like activity which exists in edothelial membrane. Thus, it is quite possible that some inhibitory activity on platelet aggregation exists in the brush border membrane of placental chorioepithelium. We, therefore, investigated the presence of such an inhibitory activity on platelet aggregation as well as its properties using a fraction of the brush border membrane.