Document Detail

Pregnancy increases myometrial artery myogenic tone via NOS- or COX-independent mechanisms.
MedLine Citation:
PMID:  22739352     Owner:  NLM     Status:  MEDLINE    
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.
Delrae M Eckman; Ridhima Gupta; Charles R Rosenfeld; Timothy M Morgan; Shelton M Charles; Heather Mertz; Lorna G Moore
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2012-06-27
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  303     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-08-16     Completed Date:  2012-11-06     Revised Date:  2013-08-18    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R368-75     Citation Subset:  IM    
Department of Pediatrics, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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MeSH Terms
Arteries / drug effects,  physiology*
Cyclooxygenase Inhibitors / pharmacology
Endothelium, Vascular / drug effects,  physiology*
Enzyme Inhibitors / pharmacology
Indomethacin / pharmacology
Middle Aged
Myometrium / blood supply*,  drug effects,  metabolism
NG-Nitroarginine Methyl Ester / pharmacology
Nitric Oxide Synthase / metabolism*
Prostaglandin-Endoperoxide Synthases / metabolism*
Vasoconstriction / drug effects,  physiology*
Vasodilation / drug effects,  physiology
Grant Support
Reg. No./Substance:
0/Cyclooxygenase Inhibitors; 0/Enzyme Inhibitors; 50903-99-6/NG-Nitroarginine Methyl Ester; 53-86-1/Indomethacin; EC Oxide Synthase; EC Synthases

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