Mechanisms of Nitrite Mediated Hepatic Preconditioning: Role of the Mitochondria

亚硝酸盐介导的肝脏预处理机制：线粒体的作用

• 批准号: 7219324
• 负责人: John Winter Calvert
• 金额: $ 4.6万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-01 至 2009-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7219324
• 关键词: calcium flux; cell morphology; cytochrome c; cytoprotection; ischemic preconditioning; liver ischemia /hypoxia; liver transplantation; mitochondria; mitochondrial membrane; nitric oxide; nitrites; oxidative phosphorylation; postdoctoral investigator; potassium channel; protein kinase A; protein kinase C; reperfusion; secretion

DESCRIPTION (provided by applicant): 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 consideration 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 hepatic I/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-protection of 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.

描述（由申请人提供）：肝缺血/再灌注（I/R）导致的肝功能障碍或衰竭是接受肝移植手术的患者发病和死亡的主要原因。目前，尚不存在治疗策略，而且供体供需之间不断扩大的差距迫使人们考虑尸体或脂肪变性图，这些图很容易受到 I/R 的影响。由于细胞和器官衰竭的恢复可能需要多个层面的干预，因此过去几年探索的最有前途的 I/R 损伤保护策略是预处理。因此，模拟这些效应的缺血预处理或药物干预可能最有可能改善肝移植和肝脏手术的临床结果。最近，亚硝酸盐通过生成一氧化氮 (NO) 已被证明在肝 I/R 情况下具有细胞保护作用，这表明亚硝酸盐可能作为 NO 的生物储存储备，在保护组织免受缺血性损伤方面发挥着关键作用。此外，我们实验室的初步数据表明，I/R 前 24 小时服用亚硝酸盐可以保护肝脏免受损伤。此外，发现亚硝酸盐预处理可以减弱 L/R 诱导的线粒体呼吸抑制。因此，本提案的目的是深入研究线粒体在亚硝酸盐介导的肝预处理中的作用，其中心假设是亚硝酸盐预处理在肝I/R后保留线粒体的结构和功能，从而减轻肝细胞损伤。这项研究的基本原理是，确定亚硝酸盐预处理的机制可以为将临床应用扩展到面临肝移植或肝脏手术的患者提供基础。因此，我们计划通过追求两个具体目标来检验我们的中心假设并实现拟议研究的目标。具体目标 1 将通过评估线粒体基质体积、线粒体膜电位、线粒体钙吸收、不同复合物的线粒体呼吸、ATP 产生、氧化还原电位、ROS 产生来探索线粒体的保护，进一步扩展我们的初步数据，最后将细胞色素 C 从线粒体释放到细胞质中。具体目标 2 将退后一步，通过检查线粒体 K+ 通道的作用来探索亚硝酸盐预处理的信号传导机制。我们认为，亚硝酸盐通过转化为 NO，分别通过 PKC 和 PKA 的分子信号传导介导线粒体 K+ 通道、mKATP 和 mKCa 的打开，从而保护线粒体免受随后的 I/R 损伤。