This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Jain, V. Articles by Garfield, R. E. Search for Related Content PubMed PubMed Citation Articles by Jain, V. Articles by Vedernikov, Y. P. Articles by Saade, G. R. Articles by Chwalisz, K. Articles by Garfield, R. E. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB INDOMETHACIN POTASSIUM Social Bookmarking                   What's this?

Relaxation Kinetics of Rat Aorta During Pregnancy

Yuri P. Vedernikov, MD, PhD

George R. Saade, MD

Kristof Chwalisz, MD, PhD

Departments of Obstetrics and Gynecology and Physiology and Biophysics, The University of Texas Medical Health, Galveston, Texas, and Research Laboratories of Schering MD Berlin, Germany

Robert E. Garfield, PhD

Departments of Obstetrics and Gynecology and Physiology and Biophysics, The University of Texas Medical Health, Galveston, Texas, and Research Laboratories of Schering MD Berlin, Germany; Division of Reproductive Sciences, Department of Obstetrics and Gynecology, The University of Texas Medical Branch, 301 University Boulevard, Rt J-62, Galveston, TX 77555-1062 rgarfiel{at}marlin.utmb.edu

Objective: To examine the hypothesis that kinetics of vasorelaxation are altered during pregnancy.

Methods: Rings of aorta from rats at different stages of pregnancy (early, late, and term) and from nonpregnant female rats were precontracted with high-K⁺ and then allowed to relax in normal-K⁺ physiologic saline solution. The time to reach 50% and 80% relaxation were determined in the absence or presence of a cycloxygenase inhibitor (indomethacin) and a nitric oxide synthase inhibitor (N-nitro-L-arginine methyl ester) or after removal of the endothelium.

Results: The aortic relaxation was progressively faster in later stages of gestation. N-nitro-L-arginine methyl ester and indomethacin had no significant effect whereas removal of hte endothelium caused a slowing of relaxation in all the groups. Even in the presence of N-nitro-L-arginine methyl ester and indomethacin or after de-endothelization, the relaxation remained faster at term as compared with the other groups.

Conclusion: Aortic relaxation is faster in the presence of endothelium. The effect of endothelium on relaxation is independent of nitric oxide synthase or cycloxygenase systems. Progression of gestation is associated with acceleration of aortic relaxation, which cannot be totally ascribed to an endothelial factor and may involve a change intrinsic to the vascular smooth muscle. Faster relaxation kinetics of the vasculature during pregnancy may be a mechanism to decrease peripheral vascular resistance.

Key Words: Rat aorta • pregnancy • endothelium • vascular smooth muscle • relaxation kinetics

Journal of the Society for Gynecologic Investigation, Vol. 5, No. 2, 81-86 (1998)
DOI: 10.1177/107155769800500206


CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?