Elevation of nitrate levels in pregnant ewes and their fetuses

D. Yang, U. Lang, S. G. Greenberg, Leslie Myatt, K. E. Clark

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

OBJECTIVE: Nitric oxide is e 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 Griess reagent. RESULTS: Arterial plasma nitrate concentrations in the pregnant sheep were significantly elevated compared with those of nonpregnant sheep (5.0 ± 0.9 vs 2.5 ± 0.6 μmol/L, p <0.05). The urinary nitrate concentrations were also significantly increased in the pregnant sheep compared with those of nonpregnant sheep (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 μmol/L, p <0.01), whereas amniotic fluid concentrations were extremely high (133.8 ± 13.8 μmol/L, n = 3). No venous-arterial differences were measurable across either the maternal or fetal sides of the placenta. CONCLUSION: Nitrate concentrations in pregnant sheep 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.

Original languageEnglish (US)
Pages (from-to)573-577
Number of pages5
JournalAmerican Journal of Obstetrics and Gynecology
Volume174
Issue number2
DOIs
StatePublished - 1996
Externally publishedYes

Fingerprint

Nitrates
Fetus
Sheep
Mothers
Nitric Oxide
Amniotic Fluid
Nitrites
Urine
Umbilicus
Pregnancy
Umbilical Veins
Femoral Vein
Femoral Artery
Ambulatory Surgical Procedures
Vasodilator Agents
Vascular Resistance
Placenta
Blood Vessels
Creatinine
Catheters

Keywords

  • fetus
  • Nitrate levels
  • pregnant ewe

ASJC Scopus subject areas

  • Medicine(all)
  • Obstetrics and Gynecology

Cite this

Elevation of nitrate levels in pregnant ewes and their fetuses. / Yang, D.; Lang, U.; Greenberg, S. G.; Myatt, Leslie; Clark, K. E.

In: American Journal of Obstetrics and Gynecology, Vol. 174, No. 2, 1996, p. 573-577.

Research output: Contribution to journalArticle

Yang, D. ; Lang, U. ; Greenberg, S. G. ; Myatt, Leslie ; Clark, K. E. / Elevation of nitrate levels in pregnant ewes and their fetuses. In: American Journal of Obstetrics and Gynecology. 1996 ; Vol. 174, No. 2. pp. 573-577.
@article{a1cbeb01bace4691af2a71e85c650fa0,
title = "Elevation of nitrate levels in pregnant ewes and their fetuses",
abstract = "OBJECTIVE: Nitric oxide is e 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 Griess reagent. RESULTS: Arterial plasma nitrate concentrations in the pregnant sheep were significantly elevated compared with those of nonpregnant sheep (5.0 ± 0.9 vs 2.5 ± 0.6 μmol/L, p <0.05). The urinary nitrate concentrations were also significantly increased in the pregnant sheep compared with those of nonpregnant sheep (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 μmol/L, p <0.01), whereas amniotic fluid concentrations were extremely high (133.8 ± 13.8 μmol/L, n = 3). No venous-arterial differences were measurable across either the maternal or fetal sides of the placenta. CONCLUSION: Nitrate concentrations in pregnant sheep 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.",
keywords = "fetus, Nitrate levels, pregnant ewe",
author = "D. Yang and U. Lang and Greenberg, {S. G.} and Leslie Myatt and Clark, {K. E.}",
year = "1996",
doi = "10.1016/S0002-9378(96)70430-1",
language = "English (US)",
volume = "174",
pages = "573--577",
journal = "American Journal of Obstetrics and Gynecology",
issn = "0002-9378",
publisher = "Mosby Inc.",
number = "2",

}

TY - JOUR

T1 - Elevation of nitrate levels in pregnant ewes and their fetuses

AU - Yang, D.

AU - Lang, U.

AU - Greenberg, S. G.

AU - Myatt, Leslie

AU - Clark, K. E.

PY - 1996

Y1 - 1996

N2 - OBJECTIVE: Nitric oxide is e 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 Griess reagent. RESULTS: Arterial plasma nitrate concentrations in the pregnant sheep were significantly elevated compared with those of nonpregnant sheep (5.0 ± 0.9 vs 2.5 ± 0.6 μmol/L, p <0.05). The urinary nitrate concentrations were also significantly increased in the pregnant sheep compared with those of nonpregnant sheep (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 μmol/L, p <0.01), whereas amniotic fluid concentrations were extremely high (133.8 ± 13.8 μmol/L, n = 3). No venous-arterial differences were measurable across either the maternal or fetal sides of the placenta. CONCLUSION: Nitrate concentrations in pregnant sheep 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.

AB - OBJECTIVE: Nitric oxide is e 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 Griess reagent. RESULTS: Arterial plasma nitrate concentrations in the pregnant sheep were significantly elevated compared with those of nonpregnant sheep (5.0 ± 0.9 vs 2.5 ± 0.6 μmol/L, p <0.05). The urinary nitrate concentrations were also significantly increased in the pregnant sheep compared with those of nonpregnant sheep (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 μmol/L, p <0.01), whereas amniotic fluid concentrations were extremely high (133.8 ± 13.8 μmol/L, n = 3). No venous-arterial differences were measurable across either the maternal or fetal sides of the placenta. CONCLUSION: Nitrate concentrations in pregnant sheep 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.

KW - fetus

KW - Nitrate levels

KW - pregnant ewe

UR - http://www.scopus.com/inward/record.url?scp=0030070153&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030070153&partnerID=8YFLogxK

U2 - 10.1016/S0002-9378(96)70430-1

DO - 10.1016/S0002-9378(96)70430-1

M3 - Article

C2 - 8623787

AN - SCOPUS:0030070153

VL - 174

SP - 573

EP - 577

JO - American Journal of Obstetrics and Gynecology

JF - American Journal of Obstetrics and Gynecology

SN - 0002-9378

IS - 2

ER -