Uterine prostaglandin concentrations following fetal death in sheep

Abstract

Concentrations of prostaglandin E (PGE), PGF and 6-oxo-PGF 1α (the hydrolytic product of PGI 2) were measured by radioimmunoassay (RIA) in myometrium, endometrium, cotyledons, amnion and chorioallantois taken from different uterine areas from chronically catheterized sheep bearing fetuses which had died 12–26 h previously (n=4) or 34–72 h previously (n=4). These two groups of animals were designated fetuses dead <30 h and >30 h respectively. The time of fetal death was assessed on the basis of fetal heart rate and blood gases. At the time of the tissue collection the ewes were between 123 and 130 days after mating. For comparative purposes, tissues also were collected from four sheep bearing live chronically catheterized fetuses at 130 days of gestation. For myometrium, concentration of PGF, PGE and 6-oxo-PGF 1α were significantly higher in sheep bearing dead fetuses, compared to those bearing live fetuses. Analysis of variance also showed a significant effect of uterine area on myometrial PGE concentrations, concentrations being higher in tubal areas than elsewhere. Concentrations of PGE, PGF and 6-oxo-PGF 1α were higher in endometrium taken from uteri containing dead fetuses. In cotyledons, concentrations of PGF and 6-oxo-PGF 1α but not PGE, were significant elevated following fetal death. Concentrations of 6-oxo-PGF 1α, but not PGE or PGF, were elevated in both chorioallantois and amnion of sheep bearing dead fetuses, compared to those bearing live fetuses. In association with elevated PG concentrations, there was a progressive increase in the frequency and maximum amplitude of uterine contractions. These results show that PG concetrations are elevated following fetal death in sheep, and suggest an association between elevated PG concentrations and delivery of the dead fetus.