Arginine flux and nitric oxide production during human pregnancy and postpartum

J Soc Gynecol Investig. 2003 Oct;10(7):400-5. doi: 10.1016/s1071-5576(03)00137-0.


Objective: To compare second-trimester, third-trimester, and postpartum arginine flux and nitric oxide production using infusions of the stable isotope L-[(15)N(2)]-arginine in normal human gestation.

Methods: Kinetic measurements were made in pregnant volunteers with uncomplicated singleton gestations in mid gestation, late gestation, and more than 8 weeks postpartum. A bolus of 4.95 micromol/kg of labeled arginine was administered, followed by an infusion at 4.95 micromol/kg per hour for 6 hours. The isotopic enrichment of plasma arginine and nitrite or nitrate (NO(x)) was determined by gas chromatography, mass spectrometry, or both. We used the Kolmogorov-Smirnov test for normality, repeated-measures analysis of variance, and Newman-Keuls test. P <.05 denoted statistical significance.

Results: The rate of turnover of the intravascular NO(x) pool was significantly higher in mid gestation compared with late gestation and almost reached statistical significance when compared with postpartum values (6.2 +/- 0.9 versus 4.3 +/- 0.8 [P <.02] versus 3.7 +/- 2.1% pool/hour; P =.08). Arginine flux was significantly higher in early compared with late gestation and postpartum (107.8 +/- 13.9 versus 72.5 +/- 16.1 versus 82 +/- 8.8 micromol/kg per hour, respectively; P <.01).

Conclusion: Arginine and nitric oxide production is higher in mid gestation. This suggests a role for nitric oxide in early cardiovascular adaptation in human gestations.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Arginine / administration & dosage
  • Arginine / metabolism*
  • Female
  • Gestational Age
  • Humans
  • Kinetics
  • Nitric Oxide / biosynthesis*
  • Nitrogen Isotopes
  • Postpartum Period*
  • Pregnancy


  • Nitrogen Isotopes
  • Nitric Oxide
  • Arginine