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PubMed · 11668079

Pregnancy and estradiol decrease GTPase activity in the guinea pig uterine artery.

I A Buhimschi·G Hall·L P Thompson·C P Weiner
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Abstract

The mechanisms by which pregnancy redistributes cardiac output in an organ-specific manner are poorly understood. We propose that it is consequential to estrogen-mediated alterations in G protein-mediated signal transduction. Aortas and uterine (UAs) and mesenteric arteries (MAs) were obtained from late-pregnant, nonpregnant, or ovariectomized guinea pigs chronically treated with 17beta-estradiol. High-affinity GTPase activity was assayed enzymatically. The cGMP generated in response to the endothelium-dependent agonist ACh was measured in UAs incubated with or without cholera toxin (CTX, which inhibits G(s)alpha). Pregnancy significantly decreased UA but not aorta or MA GTPase activity. 17beta-Estradiol decreased UA GTPase activity compared with untreated ovariectomized animals. ACh increased cGMP in pregnant but not nonpregnant UAs. Pretreatment of nonpregnant UAs with CTX increased ACh-induced cGMP levels similar to pregnancy. Thus pregnancy and estradiol decrease the GTPase activity of a CTX-sensitive G protein in UAs, increasing receptor-dependent cGMP release. This alteration in receptor-mediated G protein coupling in UAs may contribute to the characteristic cardiovascular adaptation to pregnancy.

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AcetylcholineAdjuvants, ImmunologicAnimalsArteriesBradykininCholera ToxinCyclic GMPEstradiolFemaleGTP PhosphohydrolasesGuinea PigsNitric OxideOvariectomyPregnancyPregnancy, AnimalSecond Messenger SystemsUterusVasodilator AgentsJournal Article

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I A Buhimschi, G Hall, L P Thompson, C P Weiner. 2001. Pregnancy and estradiol decrease GTPase activity in the guinea pig uterine artery.. https://doi.org/10.1152/ajpheart.2001.281.5.h2168

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