Fetal Sex Does Not Impact Placental Blood Flow or Placental Amino Acid Transfer in Late Gestation Pregnant Sheep With or Without Placental Insufficiency

2021 ◽  
Author(s):  
Laura D. Brown ◽  
Claire Palmer ◽  
Lucas Teynor ◽  
Brit H. Boehmer ◽  
Jane Stremming ◽  
...  
Keyword(s):  
Blood Flow ◽  
Amino Acid ◽  
Placental Insufficiency ◽  
Late Gestation ◽  
Fetal Sex ◽  
Pregnant Sheep ◽  
Placental Blood ◽  
Placental Blood Flow

Fever and regional blood flows in wethers and parturient ewes

1988 ◽  
Vol 65 (1) ◽  
pp. 165-172 ◽  
Author(s):  
C. M. Blatteis ◽  
J. R. Hales ◽  
A. A. Fawcett ◽  
T. A. Mashburn
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Full Term ◽  
Blood Flows ◽  
Pregnant Sheep ◽  
Regional Blood Flows ◽  
Placental Blood ◽  
Placental Blood Flow

To determine whether the reported absence of fever in full-term-pregnant ewes might be associated with shifts of regional blood flows from thermogenic tissues to placenta during this critical period, fevers were induced twice by injections of Escherichia coli lipopolysaccharide (LPS, 0.25 microgram/kg iv) into each of six Merino ewes from 8 to 1 days prepartum, and their regional blood flow distribution was measured with radioactive, 15-microns-diam microspheres before and during the rise in fever (when their rectal temperature had risen approximately 0.4 degree C). Unexpectedly, fever always developed, rising to heights not significantly different at any time before parturition [4-8 days prepartum = 0.81 +/- 0.23 degree C (SE); 1-3 days prepartum = 0.75 +/- 0.17 degree C) and similar to those in three wethers treated similarly (0.90 +/- 0.10 degree C). Generally, during rising fever, blood flow in the ewes shifted away from heat loss tissues (e.g., skin, nose) to heat production tissues (e.g., shivering muscle, fat) and cardiac output increased; blood flow through redistribution organs (e.g., splanchnic bed) decreased. The reverse occurred during defervescence. Utero-placental blood flow remained high in the febrile ewes. These regional blood flow distributions during febrigenesis and lysis are essentially the same as those during exposures to ambient cold and heat, respectively. Some differences in the responses of cardiac output and its redistribution, however, were apparent between wethers and pregnant ewes. We conclude that 1) the previously reported "absence of fever in the full-term-pregnant sheep" should not be regarded as a general phenomenon and 2) full-term-pregnant sheep support fever production without sacrificing placental blood flow.

Fetal responses to acute maternal cocaine injection in sheep

1993 ◽  
Vol 265 (1) ◽  
pp. H9-H14
Author(s):  
C. A. Gleason ◽  
H. Iida ◽  
T. P. O'Brien ◽  
M. D. Jones ◽  
E. J. Cone ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Brain Stem ◽  
Blood Gases ◽  
Vascular Effects ◽  
Arterial Blood ◽  
Pregnant Sheep ◽  
Placental Blood ◽  
Cerebral Vasodilation ◽  
Placental Blood Flow

Maternal cocaine abuse has been associated with neonatal neurological and neurobehavioral problems of unknown pathogenesis. We administered a single intravenous dose of cocaine (2 mg/kg) to 12 unanesthetized pregnant sheep; their fetuses had been catheterized in utero 2 days before the study. We measured fetal cerebral blood flow (CBF), cerebral metabolic rate of O2 (CMRO2), mean arterial blood pressure (MAP), and blood gases before and 2, 5, 15, and 30 min after maternal cocaine injection. Fetal CBF increased by 37 +/- 33% (mean +/- SD) at 5 min and returned to baseline by 15 min. Regional brain blood flow changes paralleled CBF changes with the greatest increases occurring in cerebellum (54 +/- 43%) and brain stem (54 +/- 52%). Cerebral vascular resistance was decreased for cerebellum (22%) and brain stem (19%) but was unchanged for cerebral hemispheres and caudate. Increased CBF at 5 min was associated with a 20 +/- 9% increase in fetal MAP and a 38 +/- 13% decrease in fetal arterial O2 content. Fetal CMRO2 was unchanged. There was a decrease in fetal intestinal blood flow at 2 min, an increase in myocardial, adrenal, and renal blood flow at 5 min, and no change in placental blood flow. Maternal cocaine injection causes fetal hypoxemia, hypertension, and increased CBF. Possible mechanisms for cerebral vasodilation (in some areas) include hypoxemia, impaired autoregulatory response to increased blood pressure, and/or direct or indirect vascular effects of cocaine or its metabolites.

scholarly journals The effects of maternal position, in late gestation pregnancy, on placental blood flow and oxygenation: An MRI study

2020 ◽  
Author(s):  
Sophie Couper ◽  
Alys Clark ◽  
John M D Thompson ◽  
Dimitra Flouri ◽  
Rosalind Aughwane ◽  
...  
Keyword(s):  
Blood Flow ◽  
Late Gestation ◽  
Placental Blood ◽  
Mri Study ◽  
Placental Blood Flow

Chronic maternal hypertension characterized by renal dysfunction is associated with reduced placental blood flow during late gestation in rabbits

2010 ◽  
Vol 298 (4) ◽  
pp. R1043-R1049 ◽  
Author(s):  
Adelle M. McArdle ◽  
Claire T. Roberts ◽  
Devaki Maduwegedera ◽  
Rebecca L. Flower ◽  
Kate M. Denton
Keyword(s):  
Blood Flow ◽  
Sham Group ◽  
Moderate Hypertension ◽  
Mild Hypertension ◽  
Placental Weight ◽  
Late Gestation ◽  
Maternal Hypertension ◽  
Placental Blood ◽  
Placental Efficiency ◽  
Placental Blood Flow

Maternal hypertension associated with renal disease is a common pregnancy complication. Previously, we have shown in a rabbit model of mild hypertension that offspring from hypertensive mothers have increased blood pressure as adults. In human pregnancy, hypertension has been associated with decreased utero-placental blood flow. The aim of this study was to determine placental blood flow (PBF) in mild (2-kidney-1-wrapped; 2K-1W) and moderate (2-kidney-2-wrapped; 2K-2W) rabbit models of maternal hypertension. We hypothesized that PBF would be inversely related to the severity of the hypertension. PBF and renal blood flow (RBF) were measured using microspheres on day 28 of a 32-day gestation, in normotensive (sham), 2K-1W, and 2K-2W hypertensive groups. Mean arterial pressure (MAP, ∼7 mmHg, P < 0.05) was increased, and RBF (∼35%, P < 0.05) was reduced in the 2K-1W and 2K-2W (MAP ∼20 mmHg, P < 0.01; RBF ∼53%, P < 0.05) groups compared with the sham group. In the 2K-1W group, PBF fell by ∼12% ( P = 0.08) and fetal-to-placental weight ratio increased by ∼12% ( P < 0.01) compared with the sham group, reflecting an increase in the functional capacity of the placenta to deliver nutrients to the fetus. In the 2K-2W group, PBF decreased ∼51% ( P < 0.05) compared with the sham group, without changes in placental efficiency. Thus, in late gestation, placental blood flow was significantly reduced in the moderate hypertension group, without accompanying changes in fetal or placental weight or placental efficiency. In contrast, mild hypertension resulted in an increase in placental efficiency, without significant changes in placental blood flow. These findings suggest that mild and moderate hypertension may alter placental delivery of nutrients via differing mechanisms dependent upon the severity of the hypertension.

scholarly journals Evaluation of Placental Blood Flow in Patients with Placental Insufficiency

2017 ◽  
Vol 7 (1) ◽  
pp. 28-31
Author(s):  
Julia Dobrokhotova ◽  
◽  
Sophia Zalesskaya ◽  
Elena Zubareva ◽  
Andrey Zubarev ◽  
...  
Keyword(s):  
Blood Flow ◽  
Placental Insufficiency ◽  
Placental Blood ◽  
Placental Blood Flow

scholarly journals Non-invasive evaluation of placental blood flow: lessons from animal models

Reproduction ◽  
2017 ◽  
Vol 153 (3) ◽  
pp. R85-R96 ◽  
Author(s):  
E Mourier ◽  
A Tarrade ◽  
J Duan ◽  
C Richard ◽  
C Bertholdt ◽  
...  
Keyword(s):  
Blood Flow ◽  
Animal Models ◽  
Ultrasound Contrast Agents ◽  
Valuable Insight ◽  
Non Invasive ◽  
Placental Blood ◽  
2D And 3D ◽  
Reliable Methods ◽  
Placental Blood Flow ◽  
Invasive Evaluation

In human obstetrics, placental vascularisation impairment is frequent as well as linked to severe pathological events (preeclampsia and intrauterine growth restriction), and there is a need for reliable methods allowing non-invasive evaluation of placental blood flow. Uteroplacental vascularisation is complex, and animal models are essential for the technical development and safety assessment of these imaging tools for human clinical use; however, these techniques can also be applied in the veterinary context. This paper reviews how ultrasound-based imaging methods such as 2D and 3D Doppler can provide valuable insight for the exploration of placental blood flow both in humans and animals and how new approaches such as the use of ultrasound contrast agents or ultrafast Doppler may allow to discriminate between maternal (non-pulsatile) and foetal (pulsatile) blood flow in the placenta. Finally, functional magnetic resonance imaging could also be used to evaluate placental blood flow, as indicated by studies in animal models, but its safety in human pregnancy still requires to be confirmed.

Effect of terbutaline sulphate on ovarian, uterine and maternal placental blood flow in the anaesthetized guinea pig

1978 ◽  
Vol 53 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Lena Mårtensson ◽  
Per-Ove B. Sjöquist ◽  
Leif Bjellin ◽  
Anthony M. Carter
Keyword(s):  
Blood Flow ◽  
Guinea Pig ◽  
Terbutaline Sulphate ◽  
Placental Blood ◽  
Placental Blood Flow

Fetal cardiac bypass alters regional blood flows, arterial blood gases, and hemodynamics in sheep

1992 ◽  
Vol 263 (3) ◽  
pp. H919-H928 ◽  
Author(s):  
S. M. Bradley ◽  
F. L. Hanley ◽  
B. W. Duncan ◽  
R. W. Jennings ◽  
J. A. Jester ◽  
...  
Keyword(s):  
Blood Flow ◽  
Blood Gases ◽  
Arterial Blood Gases ◽  
Blood Flows ◽  
Arterial Blood ◽  
Cardiac Bypass ◽  
Regional Blood Flows ◽  
Placental Blood ◽  
Fetal Organs ◽  
Placental Blood Flow

Successful fetal cardiac bypass might allow prenatal correction of some congenital heart defects. However, previous studies have shown that fetal cardiac bypass may result in impaired fetal gas exchange after bypass. To investigate the etiology of this impairment, we determined whether fetal cardiac bypass causes a redistribution of fetal regional blood flows and, if so, whether a vasodilator (sodium nitroprusside) can prevent this redistribution. We also determined the effects of fetal cardiac bypass with and without nitroprusside on fetal arterial blood gases and hemodynamics. Eighteen fetal sheep were studied in utero under general anesthesia. Seven fetuses underwent bypass without nitroprusside, six underwent bypass with nitroprusside, and five were no-bypass controls. Blood flows were determined using radionuclide-labeled microspheres. After bypass without nitroprusside, placental blood flow decreased by 25–60%, whereas cardiac output increased by 15–25%. Flow to all other fetal organs increased or remained unchanged. Decreased placental blood flow after bypass was accompanied by a fall in PO2 and a rise in PCO2. Nitroprusside improved placental blood flow, cardiac output, and arterial blood gases after bypass. Thus fetal cardiac bypass causes a redistribution of regional blood flow away from the placenta and toward the other fetal organs. Nitroprusside partially prevents this redistribution. Methods of improving placental blood flow in the postbypass period may prove critical to the success of fetal cardiac bypass.

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