Clinical and experimental studies have demonstrated beneficial effects of estrogens on the human cardiovascular system. Recently, however, the Women's Health Initiative study has indicated that combinational postmenopausal hormone replacement therapy may actually increase the risk of coronary artery disease (CAD), whereas studies with unopposed estrogen therapy are still ongoing. Clearly, there is much confusion concerning the physiological and/or therapeutic effects of estrogen. Because CAD is the most common cause of death for both women and men in the United States, a major challenge facing biomedical research is to identify and characterize the molecular basis of estrogen action on the coronary circulation. Helping to meet this challenge is the direct focus of the present proposal. We propose an integrated, comprehensive investigation of how estrogen effects coronary artery smooth muscle cells (CASMC), and thereby influences coronary blood flow. Our preliminary data indicate dual and opposite effects of estrogen on porcine coronary arteries: both relaxation and contraction. Therefore, we believe these data can shed some significant light upon one of the most important controversies in cardiovascular medicine. The hypothesis of the proposal is that estrogen can both contract and relax coronary smooth muscle by targeting a single enzyme: Type 1 or neuronal NOS, in coronary myocytes to release either a vasodilator (NO) or a vasoconstrictor (superoxide) substance to modulate Ca2+ or K+ channel activity.
Aim 1 will determine the effects of estrogen on isolated coronary arteries in vitro. Pharmacological studies will identify the signal transduction and ionic mechanisms underlying estrogen-induced contraction of coronary arteries.
Aim 2 will investigate the cellular/molecular basis of estrogen's dual effects by employing both whole-cell and single-channel patch-clamp studies to examine the effects of estrogen on calcium and potassium channels directly in single coronary myocytes.
Aim 3 will employ both molecular, biochemical, and cellular fluorescence studies to identify the NOS isoform involved in the response to estrogen, and determine the role of superoxide in estrogen-induced contraction.
Aim 4 will identify and characterize signaling molecules that link estrogen receptor activation to NOS activity (e.g., HSP90, PI3 kinase, Akt). Co-immunoprecipitation will determine estrogen-stimulated bimolecular interaction of these molecules, and we will employ molecular expression techniques to overexpress and/or knock-out critical signaling molecules. The function of these molecules will be characterized by employing cellular (NO fluorescence) and molecular (patch-clamp) functional studies, and findings will be related back to function of intact coronary arteries. The long-term goal is to understand how estrogen can either contract or relax coronary arteries, and thereby help to reconcile the apparent controversy between basic research into estrogen action and clinical trials. It is hoped that these findings will contribute to the development of new therapeutic measures which will make the potential health benefits of estrogen therapy available to both men and women of all ages.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL073890-03
Application #
7150036
Study Section
Vascular Cell and Molecular Biology Study Section (VCMB)
Program Officer
Goldman, Stephen
Project Start
2004-12-01
Project End
2008-11-30
Budget Start
2006-12-01
Budget End
2007-11-30
Support Year
3
Fiscal Year
2007
Total Cost
$324,265
Indirect Cost
Name
Georgia Regents University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
966668691
City
Augusta
State
GA
Country
United States
Zip Code
30912
Yu, Xuan; Ma, Handong; Barman, Scott A et al. (2011) Activation of G protein-coupled estrogen receptor induces endothelium-independent relaxation of coronary artery smooth muscle. Am J Physiol Endocrinol Metab 301:E882-8
Wang, Aiming; Ji, Lijuan; Shang, Wei et al. (2011) Expression of GPR30, ER? and ER? in endometrium during window of implantation in patients with polycystic ovary syndrome: a pilot study. Gynecol Endocrinol 27:251-5
Royal, Crista R; Ma, Handong; Walker, Richard et al. (2011) Estrogen signaling in microvascular arteries: parturition reduces vasodilation by reducing 17?-estradiol and nNOS. Steroids 76:991-7
White, Richard E; Gerrity, Ross; Barman, Scott A et al. (2010) Estrogen and oxidative stress: A novel mechanism that may increase the risk for cardiovascular disease in women. Steroids 75:788-93
Han, Guichun; Ma, Handong; Chintala, Rajesh et al. (2009) Essential role of the 90-kilodalton heat shock protein in mediating nongenomic estrogen signaling in coronary artery smooth muscle. J Pharmacol Exp Ther 329:850-5
Barman, Scott A; Zhu, Shu; White, Richard E (2009) RhoA/Rho-kinase signaling: a therapeutic target in pulmonary hypertension. Vasc Health Risk Manag 5:663-71
Zhu, Shu; White, Richard E; Barman, Scott A (2008) Role of phosphodiesterases in modulation of BKCa channels in hypertensive pulmonary arterial smooth muscle. Ther Adv Respir Dis 2:119-27
Han, Guichun; Ma, Handong; Chintala, Rajesh et al. (2007) Nongenomic, endothelium-independent effects of estrogen on human coronary smooth muscle are mediated by type I (neuronal) NOS and PI3-kinase-Akt signaling. Am J Physiol Heart Circ Physiol 293:H314-21
Han, Guichun; Yu, Xiuping; Lu, Luo et al. (2006) Estrogen receptor alpha mediates acute potassium channel stimulation in human coronary artery smooth muscle cells. J Pharmacol Exp Ther 316:1025-30
Burnette, Jason O; White, Richard E (2006) PGI2 opens potassium channels in retinal pericytes by cyclic AMP-stimulated, cross-activation of PKG. Exp Eye Res 83:1359-65

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