Pathways of Succinate Accumulation and Adenine Nucleotide Depletion in Cardiac Ischemia

项目摘要/摘要 心脏用于收缩的能量主要由有氧呼吸产生。这一过程包括 氧化碳底物来推动三磷酸腺苷的合成。一种必不可少的底物是氧气，它充当最终的 电子受体。没有氧气，心肌中的三磷酸腺苷会迅速耗尽。有很多种 心脏暴露在缺氧或缺氧条件下的情况。当血液流动变得 限制将氧气输送到肌肉的一部分。这会发生在缺血性心脏病中。如果血液流动 如果不及时恢复，就会导致不可逆转的损害，称为心肌梗塞。器官移植是 另一种情况是心脏在运输过程中没有血液供应。肌肉的时间长短 无氧状态决定了受者组织的健康状况。这样的情况涉及到 缺血环境引起的代谢变化在再灌流期间对心肌造成损害 是恢复的，称为缺血-再灌注损伤。其中一个变化就是琥珀酸的积累。在.期间 再灌流时，大量的琥珀酸负责产生活性氧物种(ROS)， 对心肌细胞造成氧化应激。在缺血期间出现的另一个代谢变化是脑细胞耗竭 腺嘌呤核苷酸。这个群体包括AMP、ADP和ATP，都是人体内必需的能量载体 心肌。这些分子的耗尽会导致心脏能量新陈代谢受损。鲜为人知 关于这些新陈代谢变化背后的机制。 这个项目的目标是揭示琥珀酸积累和腺嘌呤核苷酸的主要途径。 缺血心肌的耗竭。工作假说是三元酸的联合作用 (TCA)循环、苹果酸-天冬氨酸穿梭(MAS)和嘌呤核苷酸循环(PNC)提供所利用的底物 为了生产琥珀酸，进入PNC的腺核苷酸被穿梭到嘌呤的降解中 小路。缺氧离体心线粒体、缺血离体心和转基因的实验 大鼠将与心肌代谢的计算模型一起用来检验这一假设。这个 这些不同系统的代谢状态将通过代谢组学和酶抑制剂进行量化，这将是 用于评估积累和消耗的主要途径。计算模型将有助于 实验设计、提炼和检验假设。此项目中的数据将同时适用于这两个应用程序 缺血性心脏病，器官移植，缺血再灌注损伤的治疗。

Project Summary/Abstract The energy utilized by the heart for contractions is primarily made by aerobic respiration. This process consists of oxidizing carbon substrates to fuel ATP synthesis. An essential substrate is oxygen which acts as the final electron acceptor. Without oxygen, ATP is rapidly depleted from the myocardium. There are a number of scenarios where the heart is exposed to hypoxic or anoxic conditions. Ischemia occurs when blood flow becomes restricted preventing oxygen delivery to part of the muscle. This occurs in ischemic heart disease. If blood flow is not restored in time, it can lead to irreversible damage, termed myocardial infarction. Organ transplantation is another scenario where the heart is away from blood supply during transportation. The amount of time the muscle is without oxygen determines the health of the tissue for the recipient. Situations such as these that involve an ischemic environment induce metabolic changes that damage the myocardium during reperfusion when oxygen is restored, known as ischemia-reperfusion injury. One such change is succinate accumulation. During reperfusion, the immense amount of succinate is responsible for reactive oxygen species (ROS) production that puts oxidative stress on cardiomyocytes. Another metabolic change seen during ischemia is the depletion of adenine nucleotides. This group includes AMP, ADP, and ATP and are all essential energy carriers in the myocardium. The depletion of these molecules results in impaired energy metabolism in the heart. Little is known about the mechanisms behind these metabolic changes. The goal of this project is to uncover the primary pathways of succinate accumulation and adenine nucleotide depletion in ischemic myocardium. The working hypothesis is the combined actions of the tricarboxylic acid (TCA) cycle, malate-aspartate shuttle (MAS), and the purine nucleotide cycle (PNC) provide the substrate utilized for succinate production and adenine nucleotides entering the PNC are shuttled into purine degradation pathways. Experiments involving anoxic isolated heart mitochondrial, ischemic ex vivo hearts, and transgenic rats will be used jointly with computational models of myocardial metabolism to test this hypothesis. The metabolic states of these different systems will be quantified by metabolomics and enzyme inhibitors that will be used to assess primary pathways of accumulation and depletion. Computational models will help with experimental design, refining, and testing hypotheses. The data from this project will have applications for both ischemic heart disease, organ transplantation, treatments for ischemia-reperfusion injury.