Nitric oxide synthase activities in placental tissue from normotensive, pre-eclamptic and growth retarded pregnancies (original) (raw)

Placental Nitric Oxide Synthase Activity and Abnormal Umbilical Artery Flow Velocity Waveforms

Obstetrics & Gynecology, 1997

To assess the nitric oxide synthase activity in placentas from women with either normal or abnormal Doppler ultrasound umbilical artery flow velocity waveforms who delivered by elective cesarean. Methods: This prospective observational study involved 16 women admitted either for elective cesarean for standard obstetric indications (with normal umbilical artery Doppler waveform studies, n = 8) or with evidence of fetal or maternal complications of pregnancy (with abnormal umbilical artery Doppler studies, II = 8). Placental tissue was collected and frozen in liquid nitrogen immediately upon delivery. Following storage at-8OC, nitric oxide synthase activity was analyzed by measuring the conversion of [3HlLarginine to [3H]L-citrulline. Results: Placentas from women with abnormal umbilical artery flow velocity waveforms showed significantly lower mean nitric oxide synthase activity than did placentas from women with normal umbilical artery flow velocity waveforms (V,,, = 11.3 pmol/minute/mg protein versus 22.6 pmol/minute/mg protein). Conclusion: There is a statistically significant reduction in nitric oxide synthase activity in placentas from pregnancies with abnormal umbilical artery flow velocity waveforms.

Expression of nitric oxide synthase isoforms in the human placenta is not altered by labor

Endocrine journal, 2003

Nitric oxide has various biological activities including smooth muscle relaxation, anti-inflammatory activity, anti-coagulatory activity. As the human placenta is known to express nitric oxide synthases, this study investigated the possible effect of labor on the expression of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) in human placental tissues at term. Both eNOS and iNOS mRNA expression in placental tissues in labor were significantly higher than those in the amnion, chorion laeve, decidua vera and myometrium. The eNOS mRNA and protein expressions in placental tissues in labor (n = 12) were 1.6023 +/- 0.1652 (eNOS/GAPDH, mean +/- SEM) and 12.8 +/- 1.3 arbitrary units (AU), respectively, which were similar to those not in labor (n = 10), 1.5806 +/- 0.2042 (eNOS/GAPDH) and 11.4 +/- 1.8 AU. The iNOS mRNA and protein expressions in the placental tissues in labor were 1.2831 +/- 0.2436 (iNOS/GAPDH) and 10.7 +/- 2.1 AU respectively, similar to th...

Nitric oxide synthesis in placenta is increased in intrauterine growth restriction and fetal hypoxia

Collegium Antropologicum, 2008

In order to study the possible role of nitric oxide (NO) in the human placenta, we measured the concentration of its stable metabolite nitrite (NO 2-) in the placentas of women with normal pregnancies and those from pregnancies complicated by intrauterine growth restriction (IUGR) with or without fetal hypoxia. We have measured nitrites by the Griess reaction in 15 placentas from IUGR pregnancies and 12 controls. Cerebroumbilical ratio (C:U) was recorded by color Doppler ultrasound and values below 1 were considered to be a predictor for fetal hypoxia. NO 2 levels measured in pathological placentas were increased for at least 93 % as compared to control. Subjects from pregnancies complicated by IUGR and fetal hypoxia had increased NO 2 as compared to the placentas from pregnancies with IUGR and normal fetal oxygenation. NO production in placenta is increased in pregnancies with IUGR. This effect is more pronounced in those with compromised fetal oxygenation.

Compensatory feto-placental upregulation of the nitric oxide system during fetal growth restriction

PloS one, 2012

Fetal Growth Restriction is often associated with a feto-placental vascular dysfunction conceivably involving endothelial cells. Our study aimed to verify this pathogenic role for feto-placental endothelial cells and, coincidentally, demonstrate any abnormality in the nitric oxide system. Prenatal assessment of feto-placental vascular function was combined with measurement of nitric oxide (in the form of S-nitrosohemoglobin) and its nitrite byproduct, and of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine. Umbilical vein endothelial cells were also harvested to determine their gene profile. The study comprised term pregnancies with normal (n = 40) or small-for-gestational-age (n = 20) newborns, small-for-gestational-age preterm pregnancies (n = 15), and bi-chorial, bi-amniotic twin pregnancies with discordant fetal growth (n = 12). Umbilical blood nitrite (p<0.001) and S-nitrosohemoglobin (p = 0.02) rose with fetal growth restriction while asymmetric di...

Reduction of Placental Nitric Oxide Synthase Activity in Pre-Eclampsia

Clinical Science, 1997

The role of the potent vasodilator nitric oxide in the pathogenesis of pre-eclampsia is unclear. We have tested the hypothesis that placental activity of the enzyme which synthesizes nitric oxide (nitric oxide synthase) is reduced in pre-eclampsia. 2. Placentae were obtained after vaginal delivery or Caesarean section from women who had been assigned to the following groups according to standard obstetric criteria: term non-pre-eclamptic control, term pre-eclamptic, preterm non-preeclamptic control and preterm pre-eclamptic. Nitric oxide synthase activity of placental tissue homogenates was assessed by measuring conversion of r3H] L-arginine into [3H] L-citrulline in the presence of NADPH, FAD, tetrahydrobiopterin, calmodulin, CaC12, magnesium acetate and a range of L-arginine concentrations. Michaelis Menton constants (K,) amd maximum velocities of reaction (Vmax) were calculated using Lineweaver-Burk analysis. 3. Vmax was significantly reduced in both term and preterm pre-eclamptic placentae compared with placentae from corresponding gestation-matched controls. There were no significant differences in the Km values for nitric oxide synthase between any of the four groups, nor were Vmsx or K , values significantly influenced by mode of delivery. 4. These results provide evidence that human placental nitric oxide synthase activity is significantly reduced in pre-eclampsia. Such a reduction was evident at both term and preterm gestations. Reduced placental nitric oxide synthase activity may have an adverse effect on placental haemodynamic function in pre-eclampsia, and could be involved in the pathogenesis of this important and common obstetric complication.

Temporal expression of inducible nitric oxide synthase in mouse and human placenta

Molecular Human Reproduction, 1999

The aim of this study is to investigate the changes in expression and activity of inducible nitric oxide synthase (iNOS) in the developing murine embryo and mouse and human placenta. Using reverse transcriptionpolymerase chain reaction (RT-PCR), Northern blotting, and in-situ hybridization (ISH) we identified iNOS mRNA in mouse placenta at 9.5, 12, 14, 16, 18 and 20 days post coitum. Northern blot analysis demonstrated that the quantity of murine iNOS transcript was expressed at a stable level between days 12-20 although the level of calcium-independent NOS activity declined with advancing gestation. RT-PCR detected iNOSspecific mRNA in murine embryonic stem cells, but not in embryos at later stages (4-cell or blastocyst). ISH failed to show iNOS-specific mRNA in either murine placenta or the underlying myometrium on day 7, but did so in the trophoblast by day 9.5. Later in gestation, extensive labelling was observed in both spongiotrophoblast and trophoblast giant cells. iNOS mRNA was also detected both in immature human placentae (16-18 weeks) and at term, predominantly in syncytiotrophoblasts and placental artery smooth muscle. In conclusion, iNOS is constitutively expressed in mouse and human placenta at a time and in a location that suggests a role in placentation.

Maternal and Fetal Complications Due to Decreased Nitric Oxide Synthesis during Gestation

Complications of Pregnancy, 2019

Nitric oxide (NO) is synthesized from L-arginine by the constitutive NO synthase in vascular endothelial cells and plays an important role in the regulation of blood pressure and coronary vasomotion. Normal pregnancy is associated with major adaptations in maternal cardiovascular function, which help the woman to accommodate the growing fetus. The vascular endothelium is stimulated during pregnancy to release increased amounts of NO, and the abnormality in the L-arginine NO pathway may play a role in the etiology of preeclampsia. The objective of this study is to discuss the importance of nitric oxide during gestation and the maternal and fetal complications associated with decreased NO synthesis during this period. Maternal arterial hypertension due to inhibition of nitric oxide synthesis during pregnancy impairs fetal development, mainly the reduction of the wall/lumen ratio of the cardiac and renal microvasculature as well as the reduction in the number of nephrons. These changes...