Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Yang, D; Lang, U; Greenberg, SG; Myatt, L; Clark, KE.
Elevation of nitrate levels in pregnant ewes and their fetuses.
Am J Obstet Gynecol. 1996; 174(2):573-577
Doi: 10.1016/S0002-9378(96)70430-1
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- Co-Autor*innen der Med Uni Graz
- Lang Uwe
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- Abstract:
- OBJECTIVE: Nitric oxide is a potent vasodilator released by endothelial cells that may play an important role in modulating maternal and fetal vascular tone in normal pregnancy. The current study was designed to evaluate whether plasma or urine nitrite and nitrate (the metabolites of nitric oxide) concentrations are elevated in pregnant compared with those of nonpregnant sheep and whether the nitrate concentrations in the fetal circulation were increased in comparison with the maternal circulation. STUDY DESIGN: Eleven pregnant sheep and seven nonpregnant oophorectomized sheep were instrumented with catheters in the maternal and fetal femoral arteries and veins, uterine and umbilical veins, and amniotic cavity. Blood, urine, and amniotic fluid samples were collected for nitrate determination at least 5 days after surgery. After extraction nitrate was reduced to nitrite and quantitated with the Greiss reagent. RESULTS: Arterial plasma nitrate concentrations in the pregnant sheep were significantly elevated compared with those of nonpregnant sheet (5.0 +/- 0.9 vs 2.5 +/- 0.6 micromol/L, p < 0.05). The urinary nitrate concentrations were also significantly increased in the pregnant sheep compared with those of nonpregnant sheet (89.9 +/- 16.3 vs 23.1 +/- 4.5 nmol/mg creatinine, p < 0.01). Fetal plasma nitrate concentrations were ninefold higher than the maternal nitrate concentrations (43.9 +/- 7 vs 5.0 +/- 0.9 micromol/L, p < 0.01), whereas amniotic fluid concentrations were extremely high (133.8 +/- 13.8 micromol/L, n = 3). No venous-arterial differences were measurable across either the maternal or fetal sides of the placenta. CONCLUSION: Nitrate concentrations in pregnant sheet and their fetuses are increased. The increased nitrate concentrations in the maternal and fetal circulations may reflect the increased nitric oxide synthesis, which may in part mediate the cardiovascular adaptations to normal pregnancy and the low systemic and umbilical vascular resistance in the fetus.
- Find related publications in this database (using NLM MeSH Indexing)
- Amniotic Fluid - metabolism
- Animals - metabolism
- Arteries - metabolism
- Female - metabolism
- Fetal Blood - metabolism
- Nitrates - blood
- Nitric Oxide - metabolism
- Pregnancy - metabolism
- Reference Values - metabolism
- Sheep - metabolism
- Veins - metabolism
- Find related publications in this database (Keywords)
- nitrate levels
- pregnant ewe
- fetus