The effects on the fetus and placenta of graded reductions of uterine blood flow to 30-90% of control have been studied in @entity742 at days 125-143 of pregnancy. Reduction of uterine flow to 70-90% of control had little effect upon fetal oxygenation or heart rate or blood pressure but elevated fetal plasma @entity2922 concentration. Reduction of flow to 30-50% of control depressed fetal arterial and umbilical venous @entity4095 but had little effect upon @entity26 consumption unless the umbilical venous value fell below about 14 mmHg when it was depressed by up to 30%. Placental @entity26 consumption did not fall and was therefore maintained at the expense of the fetus. Fetal arterial pressure rose by 10-12 mmHg and heart rate fell by about 30 beats/min during the first 10-15 min then rose above its initial value. Plasma @entity1425 and @entity1063 concentrations rose progressively at a rate which increased with greater degrees of @entity1763 . When uterine blood flow was reduced below one-half of normal, net placental consumption of @entity413 fell and there was evidence of substantial provision of @entity413 and @entity880 from the fetus. Fetal production of @entity880 increased sharply and much of this appeared to be consumed by the placenta at a rate sufficient to account entirely for the deficit in net @entity413 consumption. The results are consistent with the hypothesis that the fetus senses even small changes in uterine blood flow that are alone insufficient to elicit significant blood gas changes. When the fall in uterine flow caused by arterial compression is relatively large, nutrient supply to the placenta is maintained at the expense of the fetus and as a result of fetal @entity413 and @entity880 production. The elevation of fetal arterial PCO2 appears to enhance fetal responses to @entity519 . The results are discussed in relation to the fetal responses to brief and prolonged reductions in uterine blood flow.

Metabolic and cardiovascular effects on fetal XXXX of sustained reduction of uterine blood flow.

@entity742 :: ('9940', 'Species') :: ['sheep'] @entity1425 :: ('MESH:D004837', 'Chemical') :: ['adrenaline'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen'] @entity519 :: ('MESH:D000860', 'Disease') :: ['hypoxia'] @entity1763 :: ('MESH:D001237', 'Disease') :: ['asphyxia'] @entity880 :: ('MESH:D019344', 'Chemical') :: ['lactate'] @entity2922 :: ('CHEBI:33567', 'Chemical') :: ['catecholamine'] @entity413 :: ('MESH:D005947', 'Chemical') :: ['glucose'] @entity1063 :: ('MESH:D009638', 'Chemical') :: ['noradrenaline'] @entity4095 :: ('MESH:C093415', 'Chemical') :: ['PO2']
@entity742 :: (9940,Species) :: ['sheep']
