[Human placental oxytocin and its increase by prostaglandin E2 and F2 alpha]

To investigate the physiological roles of human placental oxytocin (OT)-like substance, partial purification of human placental extract and placental tissue culture were carried out. 1. Both oxytocic immunoreaction in our own specific radioimmunoassay and bioaction on rat uterine contraction were observed in the larger (MW greater than or equal to 5,000) and the smaller molecular part (MW not equal to 1,000) in partially purified placental extracts by gel-filtration using Sephadex G-25. 2. Prostaglandin E2 and F2 alpha enhanced the immunoreactive OT in the cultured human term placental tissue at doses of 1-100 micrograms/ml. These findings are considered to be significant in basic studies of human placental OT-like substance.