The response of the placental circulations to prostaglandin I2 (maternal dose 20 μg/kg, fetal dose 180 μg/kg) was observed in 10 near-term sheep with chronically implanted vascular catheters. The blood flows before and 90 s after the injection of prostaglandin I2 were measured using radioactive microspheres. The injection of prostaglandin I2 to the mother decreased the blood pressure from 109±4 to 69±5 mmHg (P<0.001) and increased the vascular resistance of the maternal cytoledons from 0.166±0.018 to 0.209±0.02 mmHg (ml/min) (P<0.001). The vascular bed of the non-cotyledonary uterus vasodilated as the resistance fell from 0.705±0.02 to 0.266±0.02 mmHg/(ml/min) (P<0.001). Prostaglandin I2 caused the fetal arteriovenous pressure to fall from 37.6±1.35 to 26.0±1.6 mmHg. There was no significant change in the vascular resistance of the fetal cotyledons. We observed vasodilation in the fetal membranes as vascular resistance fell from 1.06±0.14 to 0.75±0.10 mmHg/(ml/min) (P<0.001). The infusion of prostaglandin I2 significantly depressed the response of the placenta and uterus to norepinephrine. We have not proved that prostaglandin I2 plays a direct role in maintaining placental vascular homeostasis but it may modulate the response of this organ to exogenous vasoactive agents.
|Original language||English (US)|
|Number of pages||10|
|Journal||Journal of Developmental Physiology|
|Publication status||Published - 1979|
ASJC Scopus subject areas
- Developmental Biology