Preferential increase in prostaglandin endoperoxide H synthase compared with lipoxygenase activity in sheep placenta and amnion at term pregnancy and after intrafetal glucocorticoid administration.

摘要: Prostaglandins (PGs) have been implicated as stimulants to myometrial contractility at parturition in many species. To determine whether the increased production of PGs reflects a general increase metabolism arachidonic acid or specific PG endoperoxide H synthase (PGHS) compared with lipoxygenase activities, and intrauterine sites these we examined [3H]arachidonic by homogenates placenta, amnion chorion from sheep days 78-80, 100-105, 135-140 pregnancy term (day 145). Tissues were also obtained fetuses day 125; four infused for 84 h cortisol used saline-treated controls. The endogenous content start incubation was measured capillary gas chromatography. Radioactive metabolites separated quantified reverse-phase high-pressure liquid At each gestational age converted PGs, leukotrienes (LTs) hydroxyeicosatetraenoic acids (HETEs). Conversion greater than placenta between 78 140. formation rose mean value twice that ten times chorion. In amnion, ratio PG:LT significantly relative 100-140 gestation. produced total PGHS:lipoxygenase products term. day-125 treated there significant control saline chorion; being major production. Production LTs HETEs both PGHS formed. We conclude labour induced intrafetal infusion, is site metabolism, preferential over products. These results are consistent suggestion an expression activity late pregnancy.