Background-Lower mortality rates among women with chronic heart failure than among men may depend in part on the action of female sex hormones, especially estrogens. The biological effects of estrogens are mediated by 2 distinct estrogen receptor (ER) subtypes (ER␣ and ER). The present study was undertaken to determine the role of ER in the development of chronic heart failure after experimental myocardial infarction (MI of heart failure, and contributes to impaired expression of Ca 2ϩ -handling proteins in chronic heart failure after MI. Further studies are required to delineate the relative importance of cardiac and vascular effects of ER and the role of ER␣ in the development of heart failure.
MRI of total sodium (Na) content may allow assessment of myocardial viability, but information on Na content in normal myocardium, necrotic/scar tissue, and stunned or hibernating myocardium is lacking. Thus, the aims of the study were to: 1) quantify the temporal changes in myocardial Na content postmyocardial infarction (MI) in a rat model (Protocol 1); 2) compare Na in normally perfused, hibernating, and stunned canine myocardium (Protocol 2); and 3) determine whether, in bufferperfused rat hearts, infarct scar can be differentiated from intact myocardium by 23 Na-MRI (Protocol 3). In Protocol 1, rats were subjected to LAD ligation. Infarct/scar tissue was excised at control and 1, 3, 7, 28, 56, and 128 days post-MI (N ؍ 6 -8 each), Na content was determined by 23 Na-NMR spectroscopy (MRS) and ion chromatography. Na content was persistently increased at all time points post-MI averaging 306*-160*% of control values (*P < 0.0083 vs. control). In Protocol 2, 23 Na-MRS of control (baseline), stunned and hibernating samples revealed no difference in Na. In Protocol 3, 23 Key words: 23 Na NMR; viability; myocardial infarction; hibernating; stunning; 3D-CSI In patients with a large akinetic myocardial region, assessment of myocardial viability is frequently required to decide on further therapy. Specifically, while scarred tissue cannot recover function and does not need revascularization, viable but hibernating myocardium will usually resume contractile function after revascularization with percutaneous transluminal coronary angiography (PTCA) or bypass surgery, whereas viable but stunned myocardium will recover spontaneously over time. Although it is well recognized that preoperative viability assessment is predictive of postoperative prognosis (1), all current methods to assess myocardial viability have intrinsic problems, such as patient discomfort and procedural risk (stress testing with inotropic agents using echocardiography (2) or MRI (3)), dependence on acoustic window (echocardiography), low specificity ( 201 T1-scintigraphy) or limited availability (PET) (4).Experimental 23 Na-MRI was first reported by DeLayre et al. (5) in the isolated heart, and applied in vivo by Ra et al. (6) in humans. 23 Na is among the nuclei offering the potential for the highest spatial MRI resolution due to its high NMR sensitivity and short T 1 , thereby allowing for short pulse repetition times. Considerable evidence indicates that ionic homeostasis is perturbed and tissue Na content is substantially increased during the initial hours, days after myocardial infarction (7-9). However, long-term changes in tissue Na content during postinfarction healing and scar formation have not been reported.We propose that if Na content is persistently and selectively increased in nonviable (i.e., necrotic or scarred) regions of the heart, 23 Na-MRI could provide the basis for distinguishing necrotic/scarred vs. viable myocardium and delineating infarct size. Thus, the purpose of our study was threefold: 1) to quantify temporal chang...
Abstract-Experimental and population-based studies indicate that female gender and estrogens protect the cardiovascular system against aldosterone-induced injury. Understanding the function of estrogens in heart disease requires more precise information on the role of both estrogen receptor (ER) subtypes, ER␣ and ER. Therefore, we determined whether selective activation of ER␣ or of ER would confer redundant, specific, or opposing effects on cardiovascular remodeling in aldosterone salt-treated rats. The ER␣ agonist 16␣-LE2, the ER agonist 8-VE2, and the nonselective estrogen receptor agonist 17-estradiol lowered elevated blood pressure, cardiac mass, and cardiac myocyte cross-sectional areas, as well as increased perivascular collagen accumulation and vascular osteopontin expression in ovariectomized rats receiving chronic aldosterone infusion plus a high-salt diet for 8 weeks. Uterus atrophy was prevented by 16␣-LE2 and 17-estradiol but not by 8-VE2. Cardiac proteome analyses by 2D gel electrophoresis, mass spectrometry, and peptide sequencing identified specific subsets of proteins involved in cardiac contractility, energy metabolism, cellular stress response and extracellular matrix formation that were regulated in opposite directions by aldosterone salt treatment and by different estrogen receptor agonists. We conclude that activation of either ER␣ or ER protects the cardiovascular system against the detrimental effects of aldosterone salt treatment and confers redundant, as well as specific, effects on cardiac protein expression. Nonfeminizing ER agonists such as 8-VE2 have a therapeutic potential in the treatment of hypertensive heart disease. (Hypertension. 2007;50:432-438.)
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.