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      Atorvastatin Inhibits Myocardial Cell Apoptosis in a Rat Model with Post-myocardial Infarction Heart Failure by Downregulating ER Stress Response

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          Abstract

          Objective: To determine the effect of atorvastatin on rat heart failure after myocardial infarction and to investigate the underlying mechanism of atorvastatin-mediated myocardium protection.

          Methods: Thirty-eight rats were randomly divided into three groups: a heart failure model group (model group), a heart failure plus atorvastatin treatment group (atorvastatin group) and a sham-surgery group (control group). The rat heart failure model was established by ligation of the left anterior descending of coronary arteries (LADs). Changes in hemodynamics parameters were recorded after the final drug administration. Plasma brain natriuretic peptide (BNP) concentration was determined by enzyme-linked immunosorbent assay (ELISA). Histological diagnosis was achieved by hematoxylin and eosin (H&E) and Masson's trichrome staining. The expressions of 78kDa glucose-regulated protein 78 (GRP78), caspase-12 and C/EBP homologous protein (CHOP, also known as GADD153) in myocardial cells and cultured cardiac myocytes were examined by Western blot. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was used to evaluate myocardial cell apoptosis, and flow cytometry was performed to examine the cell apoptosis of cultured cardiac myocytes.

          Results: In the atorvastatin group, myocardial cells were lined up more orderly and myocardial fibrosis level was decreased compared to the model group. The expressions of GRP78, caspase-12 and CHOP in myocardial cells were decreased in atorvastatin group. Moreover, in the atorvastatin-treated group the cell apoptosis rate was reduced and the endoplasmic reticulum (ER) stress was activated in response to heart failure and angiotensin II(Ang II) stimulation.

          Conclusions: By down-regulating GRP78, caspase-12 and CHOP expressions in myocardial cells in rat heart failure after myocardial infarction, atorvastatin treatment decreased the apoptosis of myocardial cells, suggesting the possible mechanism by which atorvastatin functions in protecting against heart failure.

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          Most cited references21

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          Oxygen, oxidative stress, hypoxia, and heart failure.

          A constant supply of oxygen is indispensable for cardiac viability and function. However, the role of oxygen and oxygen-associated processes in the heart is complex, and they and can be either beneficial or contribute to cardiac dysfunction and death. As oxygen is a major determinant of cardiac gene expression, and a critical participant in the formation of ROS and numerous other cellular processes, consideration of its role in the heart is essential in understanding the pathogenesis of cardiac dysfunction.
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            Prolonged endoplasmic reticulum stress in hypertrophic and failing heart after aortic constriction: possible contribution of endoplasmic reticulum stress to cardiac myocyte apoptosis.

            The endoplasmic reticulum (ER) is recognized as an organelle that participates in folding secretory and membrane proteins. The ER responds to stress by upregulating ER chaperones, but prolonged and/or excess ER stress leads to apoptosis. However, the potential role of ER stress in pathophysiological hearts remains unclear. Mice were subjected to transverse aortic constriction (TAC) or sham operation. Echocardiographic analysis demonstrated that mice 1 and 4 weeks after TAC had cardiac hypertrophy and failure, respectively. Cardiac expression of ER chaperones was significantly increased 1 and 4 weeks after TAC, indicating that pressure overload by TAC induced prolonged ER stress. In addition, the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells increased, and caspase-3 was cleaved in failing hearts. The antagonism of angiotensin II type 1 receptor prevented upregulation of ER chaperones and apoptosis in failing hearts. On the other hand, angiotensin II upregulated ER chaperones and induced apoptosis in cultured adult rat cardiac myocytes. We also investigated possible signaling pathways for ER-initiated apoptosis. The CHOP- (a transcription factor induced by ER stress), but not JNK- or caspase-12-, dependent pathway was activated in failing hearts by TAC. Pharmacological ER stress inducers upregulated ER chaperones and induced apoptosis in cultured cardiac myocytes. Finally, mRNA levels of ER chaperones were markedly increased in failing hearts of patients with elevated brain natriuretic peptide levels. These findings suggest that pressure overload by TAC induces prolonged ER stress, which may contribute to cardiac myocyte apoptosis during progression from cardiac hypertrophy to failure.
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              A mechanistic role for cardiac myocyte apoptosis in heart failure.

              Heart failure is a common, lethal condition whose pathogenesis is poorly understood. Recent studies have identified low levels of myocyte apoptosis (80-250 myocytes per 10(5) nuclei) in failing human hearts. It remains unclear, however, whether this cell death is a coincidental finding, a protective process, or a causal component in pathogenesis. Using transgenic mice that express a conditionally active caspase exclusively in the myocardium, we demonstrate that very low levels of myocyte apoptosis (23 myocytes per 10(5) nuclei, compared with 1.5 myocytes per 10(5) nuclei in controls) are sufficient to cause a lethal, dilated cardiomyopathy. Interestingly, these levels are four- to tenfold lower than those observed in failing human hearts. Conversely, inhibition of cardiac myocyte death in this murine model largely prevents the development of cardiac dilation and contractile dysfunction, the hallmarks of heart failure. To our knowledge, these data provide the first direct evidence that myocyte apoptosis may be a causal mechanism of heart failure, and they suggest that inhibition of this cell death process may constitute the basis for novel therapies.
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                Author and article information

                Journal
                Int J Med Sci
                ijms
                International Journal of Medical Sciences
                Ivyspring International Publisher (Sydney )
                1449-1907
                2011
                22 September 2011
                : 8
                : 7
                : 564-572
                Affiliations
                1. Department of Internal Medicine and Cardiology, China-Japan Union Hospital, Norman Bethune College of Medicine, Jilin University, China;
                2. Department of Internal Medicine and Cardiology, Second Hospital, Norman Bethune College of Medicine, Jilin University, China;
                3. Department of Internal Medicine and Endocrinology, Second Hospital, Norman Bethune College of Medicine, Jilin University, China
                Author notes
                ✉ Corresponding author: Ping Yang, Ph.D, Department of Internal Medicine and Cardiology, China-Japan Union Hospital, Norman Bethune College of Medicine, Jilin University, China. Tel: 0086-431-84995091; Fax: 0086-431-84995091; E-mail: pyang@ 123456jlu.edu.cn .

                Conflict of interest: The authors declared no conflict of interest.

                Article
                ijmsv08p0564
                10.7150/ijms.8.564
                3180773
                21960749
                4ccde380-88a2-4261-9dc2-a0a6ba9e2f21
                © Ivyspring International Publisher. This is an open-access article distributed under the terms of the Creative Commons License (http://creativecommons.org/licenses/by-nc-nd/3.0/). Reproduction is permitted for personal, noncommercial use, provided that the article is in whole, unmodified, and properly cited.
                History
                : 30 May 2011
                : 2 August 2011
                Categories
                Research Paper

                Medicine
                heart failure,atorvastatin,apoptosis.,er stress response,myocardial infarction
                Medicine
                heart failure, atorvastatin, apoptosis., er stress response, myocardial infarction

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