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）：由于肝缺血/再灌注（I/R），肝功能障碍或失败是对接受肝移植手术的患者发病率和死亡率的主要原因。当前，尚无治疗策略，捐助者的供应和需求之间的差距不断增加，这迫使考虑了尸体或脂肪态图，这对I/R非常容易受到影响。由于可能需要对一个以上水平进行干预才能恢复细胞和器官衰竭，因此在过去几年中，针对I/R伤害的最有前途的保护策略是预处理。因此，模仿这些作用的缺血性预处理或药理干预措施可能具有改善肝移植和肝脏手术临床结果的最大潜力。最近，通过一氧化氮（NO）生成的亚硝酸盐已被证明在肝I/R的环境中具有细胞保护作用，这表明亚硝酸盐可以用作无缺血保护功能的生物存储储量，从而在缺血性损伤中产生关键功能。此外，我们实验室的初步数据表明，I/R前24小时的亚硝酸盐保护肝脏免受损伤。此外，发现亚硝酸盐预处理可减轻L/R诱导的线粒体呼吸的抑制。因此，该提议的目的是深入研究线粒体在亚硝酸盐介导的肝脏预处理中的作用，中央假设是亚硝酸盐预处理保留了肝I/R后线粒体的结构和功能，从而减弱了肝细胞损伤。拟议的研究的理由是，确定亚硝酸盐预处理的机制可能为向面临肝移植或肝手术的患者扩展临床应用提供了基础。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。特定目标1将通过评估线粒体基质体积，线粒体膜电位，钙的线粒体吸收，线粒体的呼吸，不同复合物的不同复合物，ATP产生，氧化还原的生产和Cyto cyto cyto cyto cyrome cyrome cyrome cyrome cyrome探索，将进一步扩展我们的初步数据。特定的目标2将退后一步，并通过检查线粒体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，通过分别通过PKC和PKA的分子信号传播线粒体K+通道，MKATP和MKCA通过介导线粒体K+通道的开放，通过介导线粒体的I/R损伤来保护线粒体免受I/R损伤的影响。