Document Detail

Impact of pregnancy and vaginal delivery on the passive and active mechanics of the rat vagina.
MedLine Citation:
PMID:  20824342     Owner:  NLM     Status:  MEDLINE    
Remodeling of vaginal extracellular matrix and smooth muscle likely plays a critical role in reducing the risk of maternal injury during vaginal delivery by altering the mechanical properties to increase distension and reduce stress. Long-Evans rats were divided into five groups to examine the passive mechanical and active contractile properties throughout pregnancy and postpartum: virgin (n=17), mid-pregnant (Day 14-16, n=12), late-pregnant (Day 20-22, n=14), immediate postpartum (0-2 h after delivery, n=14), and 4 week postpartum (n=15). Longitudinal sections of vaginal tissue were loaded to failure uniaxially for passive mechanical or active contractile properties were examined. For passive mechanics, the tangent modulus decreased 45% by mid-pregnancy and immediately postpartum (p<0.001). The ultimate strain continuously increased up to 43% higher than virgin animals (p=0.007) in the immediate postpartum group. For active mechanics, the maximal contractile force was 36-56% lower through immediate postpartum animals, and was significantly more sensitive to K+ throughout pregnancy and postpartum (p=0.003). The changes observed in the passive and active properties of the rat vagina are consistent with what would be expected from a tissue that is remodeling to maximize its ability to distend at the time of vaginal delivery to facilitate passage of the fetus with minimal injury.
Andrew Feola; Pamela Moalli; Marianna Alperin; Robbie Duerr; Robin E Gandley; Steven Abramowitch
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-09-08
Journal Detail:
Title:  Annals of biomedical engineering     Volume:  39     ISSN:  1573-9686     ISO Abbreviation:  Ann Biomed Eng     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2010-12-24     Completed Date:  2011-04-11     Revised Date:  2013-05-30    
Medline Journal Info:
Nlm Unique ID:  0361512     Medline TA:  Ann Biomed Eng     Country:  United States    
Other Details:
Languages:  eng     Pagination:  549-58     Citation Subset:  IM    
Musculoskeletal Research Center, Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
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MeSH Terms
Delivery, Obstetric*
Elastic Modulus / physiology
Muscle Contraction / physiology*
Muscle, Smooth / physiology*
Pregnancy, Animal / physiology*
Rats, Long-Evans
Stress, Mechanical
Tensile Strength
Vagina / physiology*
Grant Support

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

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