While the impact of exogenous glucocorticoids on the fetal cardiovascular system has been well defined, relatively few studies have characterised the role of endogenous fetal glucocorticoids in the regulation of arterial blood pressure (BP) during late gestation. We have therefore infused @entity4235 , an inhibitor of @entity701 biosynthesis, into fetal @entity742 from 125 days gestation (when fetal @entity701 concentrations are low) and from 137 days gestation (when fetal @entity701 concentrations are increasing) and measured fetal plasma @entity701 , @entity4419 and ACTH, fetal systolic, diastolic and mean arterial BP, heart rate, and the fetal BP responses to increasing doses of angiotensin II (AII). At 125 days gestation, there was a significant increase in fetal plasma ACTH and @entity4419 by 24 h after (+24 h) the start of the @entity4235 infusion, and plasma @entity701 concentrations were not different at +24 h when compared with pre-infusion values. Whilst the initial fall in circulating @entity701 concentrations may have been transient, systolic, diastolic and mean arterial BP were ~5-6 mmHg lower (P < 0.05) in @entity4235 - than in vehicle-infused fetuses at 24-48 h after the start of the infusion. When @entity4235 was infused from 137/138 days gestation, there was a significant decrease in plasma @entity701 concentrations by +6 h, which was followed by an increase back to pre-infusion values. While @entity701 concentrations decreased, there was no change in fetal mean arterial BP during the first 24 h after the start of @entity4235 infusion. Mean fetal arterial BP values at 137-139 days gestation were not different in fetuses that had been infused with either vehicle or @entity4235 from 125 days gestation or with @entity4235 from 137/138 days gestation. At 137-139 days gestation, however, arterial BP responses to increasing doses of AII were significantly blunted in fetuses that had been infused with @entity4235 from 125 days gestation, when compared with fetuses that had been infused with @entity4235 from 137/138 days gestation or with vehicle from 125 days gestation. The dissociation of the gestational age increase in arterial BP and the effects of intrafetal AII on fetal arterial BP indicates that increase in fetal BP with gestational age is not entirely a result of an increased vascular responsiveness to endogenous AII. Furthermore there may be a critical window during late gestation when the actions of @entity701 contribute to the development of vascular responsiveness to AII.

The effect of intrafetal infusion of @entity4235 on arterial blood pressure and on the arterial blood pressure response to angiotensin II in the XXXX fetus during late gestation.

@entity4235 :: ('MESH:D008797', 'Chemical') :: ['metyrapone'] @entity701 :: ('MESH:D006854', 'Chemical') :: ['cortisol'] @entity742 :: ('9940', 'Species') :: ['sheep'] @entity4419 :: ('MESH:D003350', 'Chemical') :: ['11-desoxycortisol']
@entity742 :: (9940,Species) :: ['sheep']
