Flow velocity waveforms in uterine and umbilical arteriesduring the angiotensin II sensitivity test

Erkkola, Risto; Pirhonen, Jouko

doi:10.1016/0002-9378(90)90015-y

Cited by 22 publications

(22 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Whereas low to moderate intensity exercise is recommended in pregnancy, 25 previous studies have also reported that highintensity exercise significantly reduced birthweight, 15,26 perhaps mediated by reduced uterine blood flow. 27 Our data suggest that this effect is not mediated by low maternal BMI.…”

Section: Discussionmentioning

confidence: 51%

Risk factors for small‐for‐gestational‐age infants by customised birthweight centiles: data from an international prospective cohort study

McCowan

Roberts

Dekker

et al. 2010

BJOG

126

112

View full text Add to dashboard Cite

Objective To identify clinical and ultrasound variables associated with the birth of small-for-gestational-age (SGA) infants by customised centiles, subclassified according to whether their mothers were normotensive or developed hypertensive complications.Design Prospective, multicentre cohort study.Setting Participating centres of the Screening for Pregnancy Endpoints (SCOPE) study in Auckland, New Zealand, Adelaide, Australia, Manchester and London, UK, and Cork, Ireland.Population The 3513 nulliparous participants of the SCOPE study.Methods Women were interviewed at 15 ± 1 weeks, and had ultrasound growth measurements and umbilical and uterine Doppler studies at 20 ± 1 weeks. Variables associated with SGA infants were identifed using logistic regression.Main outcome measures Small for gestational age (i.e. a birthweight of less than the tenth customised centile), normotensive-SGA and hypertensive-SGA. Comparison groups for statistical analyses were non-SGA, normotensive non-SGA and hypertensive non-SGA.Results Among 376 (10.7%) SGA infants, 281 (74.7%) were normotensive-SGA and 95 (25.3%) were hypertensive-SGA. Independent risk factors for normotensive-SGA were low maternal birthweight, low fruit intake pre-pregnancy, cigarette smoking, increasing maternal age, daily vigorous exercise, being a tertiary student, head and abdominal circumference of less than the tenth centile and increasing uterine artery Doppler indices at the 20-week scan. Protective factors were: high green leafy vegetable intake pre-pregnancy, and rhesus-negative blood group. Risk factors for hypertensive-SGA were conception by in vitro fertilisation, previous early pregnancy loss and femur length of less than tenth centile at the 20-week scan.Conclusions Risk factors for infants who are SGA by customised centiles have been identified in a cohort of healthy nulliparous women. A number of these factors are modifiable; however, further studies are needed to replicate these findings.

show abstract

Section: Discussionmentioning

confidence: 51%

Risk factors for small‐for‐gestational‐age infants by customised birthweight centiles: data from an international prospective cohort study

McCowan

Roberts

Dekker

et al. 2010

BJOG

126

112

View full text Add to dashboard Cite

show abstract

“…They not only constrict the entire UVB, but also cross the placenta and directly affect fetal placental blood flow (34,54,55). Thus, ANG II may be the preferred pressor since clearance occurs across the placenta (45,51), fetal effects are uncommon at pressor doses (39), and pressor effects exceed responses in the UVB (20,21,36). Finally, these studies again demonstrate the striking similarities in the cardiovascular system of pregnant women and sheep (49,15,18).…”

Section: Perspectives and Significancementioning

confidence: 53%

“…Uterine vascular responses to ANG II are attenuated in pregnant women and sheep compared with the peripheral vasculature (20,36). In contrast, the pregnant UVB, is more sensitive to ␣-agonists than the systemic circulation (32,40,43,47).…”

Section: Discussionmentioning

confidence: 95%

See 1 more Smart Citation

Defining the differential sensitivity to norepinephrine and angiotensin II in the ovine uterine vasculature

Rosenfeld

DeSpain

Liu

2012

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

Rosenfeld CR, DeSpain K, Liu X-t. Defining the differential sensitivity to norepinephrine and angiotensin II in the ovine uterine vasculature. Am J Physiol Regul Integr Comp Physiol 302: R59-R67, 2012. First published October 26, 2011 doi:10.1152/ajpregu.00424.2011The intact ovine uterine vascular bed (UVB) is sensitive to ␣-agonists and refractory to angiotensin II (ANG II) during pregnancy; the converse occurs in the systemic circulation. The mechanism(s) responsible for these differences in uterine sensitivity are unclear and may reflect predominance of nonconstricting AT2 receptors (AT2R) in uterine vascular smooth muscle (UVSM). The contribution of the placental vasculature also is unclear. Third generation and precaruncular/placental arteries from nonpregnant (n ϭ 16) and term pregnant (n ϭ 23) sheep were used to study contraction responses to KCl, norepinephrine (NE), and ANG II (with/without ATR specific inhibitors) and determine UVSM ATR subtype expression and contractile protein content. KCl and NE increased third generation and precaruncular/ placental UVSM contractions in a dose-and pregnancy-dependent manner (P Յ 0.001). ANG II only elicited modest contractions in third generation pregnant UVSM (P ϭ 0.04) and none in precaruncular/placental UVSM. Moreover, compared with KCl and NE, ANG II contractions were diminished Ն 5-fold. Whereas KCl and ANG II contracted third generationϾϾprecaruncular/placental UVSM, NEinduced contractions were similar throughout the UVB. However, each agonist increased third generation contractions Ն 2-fold at term, paralleling increased actin/myosin and cellular protein content (P Յ 0.01). UVSM AT 1R and AT2R expression was similar throughout the UVB and unchanged during pregnancy (P Ͼ 0.1). AT 1R inhibition blocked ANG II-mediated contractions; AT 2R blockade, however, did not enhance contractions. AT 2R predominate throughout the UVB of nonpregnant and pregnant sheep, contributing to an inherent refractoriness to ANG II. In contrast, NE elicits enhanced contractility throughout the ovine UVB that exceeds ANG II and increases further at term pregnancy. placental artery; systemic artery; actin/myosin; angiotensin II receptors; ␣-agonists OVINE PREGNANCY IS ASSOCIATED with numerous cardiovascular changes (43, 48), including a Ͼ30-fold rise in uterine blood flow (UBF) and Ͼ40% increase in cardiac output. Additionally, there is development of refractoriness to the pressor effects of infused norepinephrine (NE) and angiotensin II (ANG II) in women and sheep (44,49,53). Although the ovine uterine vascular bed (UVB) also develops refractoriness to these agonists during pregnancy (32, 49), Naden and Rosenfeld (36) reported that the intact pregnant ovine UVB was more refractory to the vasoconstricting effects of ANG II than the systemic vasculature. Thus, blood pressure increased in the absence of significant decreases in uteroplacental blood flow (UPBF). In contrast, the UVB was quite sensitive to ␣-agonists, which decreased ovine UPBF at nonpressor doses, demonstrating differenc...

show abstract

“…Furthermore, during late gestation the human and ovine uteroplacental vascular beds are even more refractory to ANG II-induced vasoconstriction than the systemic vasculature [3]. This mechanism may serve to protect the uteroplacental vasculature from the normally occurring elevations in plasma ANG II [4].…”

Section: Introductionmentioning

confidence: 99%

Vascular Reactivity to Angiotensin II and Eicosanoid Production in the Human Placenta from Term and Preterm Pregnancy

Cruz

Domínguez²,

Gallardo³

et al. 2000

Gynecol Obstet Invest

View full text Add to dashboard Cite

Isolated human placental cotyledons from normal term (37–40 weeks of gestation) and preterm (26–36 weeks of gestation) labor were perfused in vitro, and the effect of angiotensin II (ANG II) and its interaction with prostanoids was measured. In the preterm group, ANG II caused greater maximal increases in perfusion pressure than in normal term pregnancies without affecting sensitivity. Also, preparations from normal term pregnancies showed a marked development of tachyphylaxis compared to placentae from preterm pregnancies. Indomethacin (10^–6 M) increased the maximum pressor response to ANG II by 33.6% in normal term, however, in preterm placentas a 39.2% reduction was observed. Infused ANG II 10^–6 M) decreased the concentrations of thromboxane B₂ and 6-keto-PGF_1α in both pregnancy groups, but this effect was not statistically different from the baseline values. In the current study, we show that the placenta of preterm pregnancies in basal conditions produce 7.6 times as much thromboxane as the normal term placenta (2,800 ± 470 vs. 366.5 ± 62 pg/min, respectively), without significant change in prostacyclin levels (preterm 88.6 ± 11.0 vs. Term 100.6 ± 30.7 pg/min). These observations provide evidence that the contribution of basally released thromboxane from placental tissue appears to contribute to abnormalities in the regulation of fetoplacental hemodynamics in premature pregnancies.

show abstract

Flow velocity waveforms in uterine and umbilical arteriesduring the angiotensin II sensitivity test

Cited by 22 publications

References 18 publications

Risk factors for small‐for‐gestational‐age infants by customised birthweight centiles: data from an international prospective cohort study

Risk factors for small‐for‐gestational‐age infants by customised birthweight centiles: data from an international prospective cohort study

Defining the differential sensitivity to norepinephrine and angiotensin II in the ovine uterine vasculature

Vascular Reactivity to Angiotensin II and Eicosanoid Production in the Human Placenta from Term and Preterm Pregnancy

Contact Info

Product

Resources

About