西地那非通过调控凋亡相关microRNA靶基因蛋白的表达减轻心肺复苏后心肌缺血再灌注损伤的机制研究

At present, post-resuscitation myocardial dysfunction remains a major cause of very low rate of survival to discharge in patients resuscitated from a sudden cardiac arrest. Postresuscitation myocardial dysfunction, an important component of the “post-cardiac arrest syndrome”, is caused by ischemia/reperfusion (I/R) injury and includes primary manifestations such as myocyte apoptosis and contractile dysfunction. Apoptosis is one of the important mechanisms of cell death in isolated myocardiums following I/R injury. MicroRNAs (miRNAs) are a newly recognized class of post-transcriptional regulators. Recent studies have shown that miRNAs expression is tightly controlled in a tissue-specific and some of them are highly and specifically expressed in cardiovascular tissues. Recent experimental and clinical studies have indicated the cardioprotective role of sildenafil during I/R injury. Our early studies have confirmed that sildenafil attenuated postresuscitation myocardial dysfunction in piget models of ventricular fibrillation. Currently, the significance of miRNA expression and possible roles of miRNAs in post-resuscitation myocardial dysfunction are not well studied. We hypothesized that administration of sildenafil will attenuate post-resuscitation myocardial dysfunction by attenuating apoptosis and regulating miRNA expressions, furthermore, ameliorating the severity of post-microcirculatory dysfunction. Based on this hypothesis, in this project the porcine model of 8 min fibrillation ventricular is established, and pigs are randomly divided into normal control group, saline control group, and sildenafil group. Changes of hemodynamic indexes, oxygen metabolism parameters, the expression of microRNA, structure and function of myocardial mitochondria, oxidative stress and apoptosis are compared. We hope to investigate if administration of sildenafil will attenuate post-resuscitation myocardial dysfunction by attenuating apoptosis and regulating miRNA expressions, furthermore, we hope to provide an important mechanistic basis of sildenafil as a potentially novel pharmacologic adjunct to resuscitation from CA for the purpose of attenuating the organ injury caused by I/R injury.

目前心肺复苏（CPR）后心功能障碍仍然是复苏成功后出院存活率低的主要原因之一。已知心肌细胞凋亡是复苏后心功能障碍发生的重要机制，抑制细胞凋亡的发生发展可减轻CPR后不可逆的心肌损伤。最新研究发现，凋亡相关微小RNA（miRNA-1和miRNA-133）可能参与了复苏后心肌细胞凋亡的发生。已知西地那非可以通过减少心肌细胞凋亡来减轻心肌缺血再灌注（I/R）损伤。前期我们已证实，西地那非可以改善复苏后血流动力学和24小时存活率，但具体机制尚不清。据此，我们推测“西地那非可能可以通过调控凋亡相关miRNA及其靶基因蛋白表达，减轻心肌细胞凋亡，从而改善复苏后心功能障碍”。本课题采用猪8分钟室颤模型，通过观察血流动力学、心肌细胞凋亡相关miRNA水平、相关细胞信号转导通路、心肌超微结构等方面的变化，探讨西地那非在复苏后心肌I/R损伤中起到保护作用的准确效应靶点，为复苏后心功能障碍的治疗提供新思路。

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