Chronic heart failure (HF) is characterized by a decreased exercise capacity with early fatigue and dyspnea. Several clinical and experimental studies have suggested that skeletal muscle abnormalities can contribute to these symptoms in heart failure patients. Changes of myosin heavy chain (MyHC) isoforms have been frequently observed in peripheral and respiratory muscles during heart failure. Pathophysiological mechanisms and intracellular signaling pathways involved on MyHCs alterations are not completely defined. Different intracellular pathways regulate skeletal muscle MyHC expression. The mitogen-activated protein kinase (MAPK) family, especially ERK, is necessary for skeletal muscle mass and phenotype maintenance. However, ERK role in this process is still controversial. In previous study, we observed ERK protein expression reduction in diaphragm muscle of heart failured-rats accompanied by fast-to-slow MyHC shift. In face of conflicting data, ERK genic silencing in isolated cells may bring some useful information about ERK role and function in skeletal muscle. Therefore, to identify specific effects of ERK protein diminish directly in skeletal muscle, ERK genic silencing will be performed. C2C12 muscle cells will be used in culture. Genic silencing will be realized by specific interference RNA. MyHC isoforms will be analyzed by electrophoresis and immunofluorescence. Cell trophism will also be analyzed by immunofluorescence. Comparison between groups will be performed by Student's t Test.
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