Pregnancy increases myometrial artery myogenic tone via NOS- or COX-independent mechanisms

Delrae M. Eckman, Ridhima Gupta, Charles R. Rosenfeld, Timothy M. Morgan, Shelton M. Charles, Heather Mertz, Lorna G. Moore

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Myogenic tone (MT) is a primary modulator of blood flow in the resistance vasculature of the brain, kidney, skeletal muscle, and perhaps in other high-flow organs such as the pregnant uterus. MT is known to be regulated by endothelium-derived factors, including products of the nitric oxide synthase (NOS) and/or the cyclooxygenase (COX) pathways. We asked whether pregnancy influenced MT in myometrial arteries (MA), and if so, whether such an effect could be attributed to alterations in NOS and/or COX. MA (200-300 μm internal diameter, 2-3 mm length) were isolated from 10 nonpregnant and 12 pregnant women undergoing elective hysterectomy or cesarean section, respectively. In the absence of NOS and/or COX inhibition, pregnancy was associated with increased MT in endothelium-intact MA compared with MA from nonpregnant women (P < 0.01). The increase in MT was not due to increased Ca 2+ entry via voltage-dependent channels since both groups of MA exhibited similar levels of constriction when exposed to 50 mM KCl. NOS inhibition (N ω-nitro-L-arginine methyl ester, L-NAME) or combined NOS/COX inhibition (L-NAME/indomethacin) increased MT in MA from pregnant women (P = 0.001 and P = 0.042, respectively) but was without effect in arteries from nonpregnant women. Indomethacin alone was without effect on MT in MA from either nonpregnant or pregnant women. We concluded that MT increases in MA during human pregnancy and that this effect was partially opposed by enhanced NOS activity.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume303
Issue number4
DOIs
StatePublished - Aug 15 2012

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Prostaglandin-Endoperoxide Synthases
Nitric Oxide Synthase
Arteries
Pregnancy
Pregnant Women
NG-Nitroarginine Methyl Ester
Indomethacin
Endothelium
Hysterectomy
Constriction
Cesarean Section
Uterus
Skeletal Muscle
Kidney
Brain

Keywords

  • Fetal growth restriction
  • Human myometrium
  • Preeclampsia
  • Pressure-induced constriction
  • Uteroplacental blood flow

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Pregnancy increases myometrial artery myogenic tone via NOS- or COX-independent mechanisms. / Eckman, Delrae M.; Gupta, Ridhima; Rosenfeld, Charles R.; Morgan, Timothy M.; Charles, Shelton M.; Mertz, Heather; Moore, Lorna G.

In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 303, No. 4, 15.08.2012.

Research output: Contribution to journalArticle

Eckman, Delrae M. ; Gupta, Ridhima ; Rosenfeld, Charles R. ; Morgan, Timothy M. ; Charles, Shelton M. ; Mertz, Heather ; Moore, Lorna G. / Pregnancy increases myometrial artery myogenic tone via NOS- or COX-independent mechanisms. In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology. 2012 ; Vol. 303, No. 4.
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