Document Detail

Contractile activity, membrane potential, and cytoplasmic calcium in human uterine smooth muscle in the third trimester of pregnancy and during labor.
MedLine Citation:
PMID:  10601927     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: This study was undertaken to investigate in human tissue samples the mechanisms underlying spontaneous and prostaglandin F(2)(alpha)-induced contractions during the final trimester of pregnancy and labor. STUDY DESIGN: Membrane potential and cytoplasmic calcium were recorded simultaneously with contraction in uterine strips obtained from the lower segment during cesarean delivery. RESULTS: Between week 28 of gestation and term there was a progressive increase in the frequency of spontaneous contractions and a decrease in the negative potential of the membrane. The response to prostaglandin F(2alpha) was biphasic. The initial excitatory component remained stable toward term. A later inhibitory component, which was underpinned by increased activity of the sodium-potassium adenosine triphosphatase pump, decreased at the time of labor. CONCLUSIONS: There is a gradual increase in excitability in uterine muscle throughout the third trimester of human pregnancy. The initial component of the prostaglandin response is a large contraction that is kept brief by a subsequent inhibitory component of the response, which ensures that full relaxation occurs between contractions.
H C Parkington; M A Tonta; S P Brennecke; H A Coleman
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of obstetrics and gynecology     Volume:  181     ISSN:  0002-9378     ISO Abbreviation:  Am. J. Obstet. Gynecol.     Publication Date:  1999 Dec 
Date Detail:
Created Date:  2000-01-20     Completed Date:  2000-01-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370476     Medline TA:  Am J Obstet Gynecol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1445-51     Citation Subset:  AIM; IM    
Department of Physiology, Monash University, Clayton, Victoria, Australia.
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MeSH Terms
Abortifacient Agents, Nonsteroidal / pharmacology
Calcium / analysis,  metabolism*
Cytoplasm / chemistry
Dinoprost / pharmacology
Gestational Age
Membrane Potentials
Myometrium / drug effects,  physiology*
Pregnancy Trimester, Third / physiology
Uterine Contraction / drug effects,  physiology*
Reg. No./Substance:
0/Abortifacient Agents, Nonsteroidal; 551-11-1/Dinoprost; 7440-70-2/Calcium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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