Mechanisms of Nitrite Mediated Hepatic Preconditioning: Role of the Mitochondria

肝脏缺血/再灌注(I/R)导致的肝功能障碍或衰竭是发病率的主要原因 以及接受过肝移植手术的患者的死亡率。目前，没有治疗方法 战略的存在，捐赠者之间不断扩大的供需缺口迫使 考虑身体或脂肪变性图形，它们非常容易受到I/R的影响。 可能需要不止一个水平来允许细胞和器官衰竭的恢复，最 最近几年探索的针对I/R损伤的有前途的保护策略是预适应。因此， 模拟这些影响的缺血预适应或药物干预可能具有最大的作用 改善肝移植和肝外科临床结果的潜力。最近，亚硝酸盐通过 一氧化氮(NO)的产生已被证明在肝脏I/R的环境中具有细胞保护作用， 提示亚硝酸盐可能作为NO的生物储备库，在组织中具有重要的功能 对缺血损伤的保护。此外，我们实验室的初步数据表明，政府 在I/R前24小时服用亚硝酸盐可保护肝脏免受损伤。此外，亚硝酸盐预适应被发现可以 减轻L/再灌注对线粒体呼吸的抑制作用。因此，这项提案的目标是 是深入研究线粒体在亚硝酸盐介导的肝脏预适应中的作用 假设亚硝酸盐预适应保护线粒体的结构和功能 在肝脏I/R后，从而减轻肝细胞损伤。建议进行这项研究的理由是 明确亚硝酸盐预适应的机制可为临床推广应用提供依据。 适用于面临肝移植或肝脏手术的患者。因此，我们计划测试我们的中心假设 并通过追求两个具体目标来实现拟议研究的目标。具体目标1将进一步 通过评估线粒体对线粒体的保护作用，扩展我们的初步数据 线粒体基质体积、线粒体膜电位、线粒体钙摄取、 不同复合体的线粒体呼吸、ATP产生、氧化还原电位、ROS产生和 最后，细胞色素C从线粒体释放到胞浆中。《特定目标2》将迈出一步 通过检测线粒体的作用探讨亚硝酸盐预适应的信号机制 K+通道。我们认为，亚硝酸盐通过转化为一氧化氮，保护线粒体免受 介导线粒体K+通道mKATP和mKCa开放的继发性I/R损伤 PKC和PKA的分子信号转导。

Liver dysfunction or failure, as a result of hepatic ischemia/reperfusion (I/R), is a leading cause of morbidity and mortality for patients who have undergone liver transplantation surgery. Currently, no therapeutic strategy exists and the ever growing gap between supply and demand for donors has forced the considertation of cadaveric or steatotic graphs, which are very susceptible to I/R. Because intervention on more than one level is likely needed to allow for the recovery of cellular and organ failure, the most promising protective strategy against I/R injury explored in the last few years is preconditioning. Therefore, ischemic preconditioning or pharmacological interventions that mimic these effects may have the greatest potential to improve clinical outcome in liver transplantation and liver surgery. Recently, nitrite through the generation of nitric oxide (NO) has been shown to have cytoprotective effects in the setting of hepaticI/R, suggesting that nitrite may serve as a biological storage reserve of NO subsurving a critical function in tissue protection from ischemic injury. Furthermore, preliminary data from our lab indicates that the administration of nitrite 24 hours prior to I/R protects the liver against injury. Moreover, nitrite preconditioning was found to attenuate the l/R-induced suppression of mitochondrial respiration. Therefore, the objective of this proposal is to delve into the role of the mitochondria in nitrite mediated hepatic preconditioning with the central hypothesis being that nitrite preconditioning preserves the structure and function of the mitochondria following hepatic I/R, thereby attenuating hepatocellular injury. The rationale for the proposed research is that identifying the mechanisms of nitrite preconditioning may provide a basis for extending the clinical application to patients facing liver transplantation or liver surgery. So, we plan to test our central hypothesis and accomplish the objective of the proposed study by pursuing two specific aims. Specific aim 1 will further expand on our preliminary data by exploring the-protectionof the mitochondria through the evaluation of mitochondrial matrix volume, mitochondrial membrane potential, mitochondiral uptake of calcium, mitochondrial respiration of the different complexes, ATP production, redox potential, ROS production, and finally the release of cytochrome C from the mitochondria into the cytosol. Specific aim 2 will take a step back and explore the signaling mechanisms of nitrite preconditioning by examining the role of mitochondrial K+ channels. We believe that nitrite, through its conversion to NO, protects the mitochondria from a subsequent I/R injury by mediating the opening of the mitochondrial K+ channels, mKATP and mKCa, via the molecular signaling of PKC and PKA, respectively.