Prostaglandin E, thromboxane B2 and 6-oxo-prostaglandin F1 alpha in amniotic fluid and maternal plasma of rhesus monkeys (Macaca mulatta) during the latter third of gestation.

The concentrations of prostaglandin E (PGE), thromboxane B2 (TXB2) and 6-oxo-prostaglandin F1 alpha (6-oxo-PGF1 alpha) were measured by radioimmunoassay in serial samples of amniotic fluid and maternal peripheral plasma in the latter third of pregnancy in rhesus monkeys (Macaca mulatta). The samples were collected under ketamine-induced anaesthesia. The concentration of PGE was undetectable in amniotic fluid until a few days before delivery when a large increase was observed in three of the five animals. There were small increases of TXB2 and 6-oxo-PGF1 alpha in amniotic fluid before delivery. In maternal plasma the concentrations of PGE, TXB2 and 6-oxo-PGF1 alpha were generally higher and more variable than in amniotic fluid and did not increase with advancing gestation. It is suggested that increased production of primary prostaglandins occurs before, and is involved in, the onset of parturition in the rhesus monkey.