XXXX placental @entity934 content and release at parturition.

@entity1 @entity1617 @entity2607 @entity934
1. Measurements were made of @entity1 placental @entity934 ( @entity1617 ) content and release into maternal and fetal circulations from placenta obtained before, during and after labours of both spontaneous and induced onsets. @entity1617 content was determined in ex vivo placental biopsies using a radio-enzymatic assay. @entity1617 release was determined by bioassay of the effluent from placental lobules perfused with amniotic fluid-like Kreb's containing @entity2607 (2.4 mumol/l). 2. @entity1617 content of placentae obtained after labour (spontaneous onset of labour, normal vaginal delivery) and during labour (spontaneous onset of labour, Caesarean section delivery) was significantly less than before labour (no labour onset, Caesarean section delivery). 3. Mean @entity1617 output into maternal vessels 1.5-4.0 h after commencement of perfusion of placentae obtained after labour (spontaneous onset of labour, normal vaginal delivery) was significantly less than from those obtained before labour (no labour onset, Caesarean section delivery). No differences were found in @entity1617 output into fetal vessels of placentae obtained before, during or after labour. 4. These results suggest a role for placental @entity1617 in the events of @entity1 labour. The decrease in @entity1617 content and maternal vascular release in placenta obtained after labour is consistent with a depletion of placental @entity1617 during labour which may indicate @entity1617 release at this time. The lack of any significant change in fetal vascular release of @entity1617 in placenta obtained before, during or after labour, raises the possibility of different roles for @entity1617 released into fetal and maternal vasculature.
