[The study on the degradation of prostacyclin activity in tissue culture supernatant of human placental villi].

To clarify the role of placental villi in maintaining microcirculation in the placenta, we investigated the action to protect the activity of prostacyclin in the tissue culture supernatant of human placental villi. 1. The platelet aggregation inhibiting activity of prostacyclin was decreased very rapidly in Ringer buffer. 2. The tissue culture supernatant of human placental villi has an action which protects the activity of prostacyclin. On the other hand, in the tissue culture supernatant of human placental decidua no such action is prominent. 3. Human chorionic gonadotropin (hCG) also has an action which protects the activity of prostacyclin. These results indicated that human placental villi play an important role in maintaining placental microcirculation by producing substances which have a protective on the activity of prostacyclin.