Circulating microparticles and endogenous estrogen in newly menopausal women

M. Jayachandran, R. D. Litwiller, W. G. Owen, V. M. Miller

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

Background: Estrogen modulates antithrombotic characteristics of the vascular endothelium and the interaction of blood elements with the vascular surface. A marker of these modulatory activities is formation of cell-specific microparticles. This study examined the relationship between blood-borne microparticles and endogenous estrogen at menopause. Methods: Platelet activation and plasma microparticles were characterized from women being screened (n = 146) for the Kronos Early Estrogen Prevention Study. Women were grouped according to serum estrogen (< 20 pg/ml; low estrogen, n = 21 or > 40 pg/ml; high estrogen, n = 11). Results: Age, body mass index, blood pressure and blood chemistries were the same in both groups. No woman was hypertensive, diabetic or a current smoker. Platelet counts, basal and activated expression of P-selectin on platelet membranes were the same, but activated expression of glycoprotein IIb/IIIa was greater in the high-estrogen group. Numbers of endothelium-, platelet-, monocyte- and granulocyte-derived microparticles were greater in the low-estrogen group. Of the total numbers of microparticles, those positive for phosphatidylserine and tissue factor were also greater in the low-estrogen group. Conclusion: These results suggest that, with declines in endogenous estrogen at menopause, numbers of procoagulant microparticles increase and thus may provide a means to explore mechanisms for cardiovascular risk development in newly menopausal women.

Original languageEnglish (US)
Pages (from-to)177-184
Number of pages8
JournalClimacteric
Volume12
Issue number2
DOIs
StatePublished - Apr 1 2009

Keywords

  • Menopause
  • Microvesicles
  • Phosphatidylserine
  • Sex hormone
  • Thrombosis

ASJC Scopus subject areas

  • Obstetrics and Gynecology

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