REGULATION OF HEART HIGH-ENERGY PHOSPHATE METABOLISM

该提案的总体目标是进一步定义这些因素 在正常和缺血后的心脏中，整合和调节 生产高能磷酸化合物，即 ATP 和 磷酸肌酸。 这些代谢物的整合被认为是 肌酸激酶反应的功能。 ATP 的净产量为 线粒体氧化磷酸化的结果。 这两个 本提案将调查流程。 模型是 分离的、灌注的、等容的工作兔心脏。 分析性的 方法将广泛涉及 31-磷核的使用 磁共振技术。 动力学和热力学方法 将被雇用。 为此，制定了三个具体目标： 1. 饱和传递和二维核磁共振研究。 这些生物物理技术 将用于测量高能磷酸盐介导的通量率 肌酸激酶和氧化磷酸化在正常和 心脏缺血后。 目标是确定 缺血引起的细胞损伤导致能量的根本变化 生产和集成。 2.体内呼吸控制研究。 最近的研究表明 腺嘌呤核苷酸对氧化磷酸化的控制涉及 ADP 在线粒体腺嘌呤核苷酸转位酶上的可用性。 该假设将在体内使用步速引起的变化进行测试 具有对心肌分级施加压力的功能。 假设 肌酸激酶的细胞质形式处于“接近平衡”状态，可以使用 用于计算游离 ADP 的该反应的平衡常数 内心的内容。 这将与费率的变化相关 耗氧量，估计 ADP 诱导的表观公里数 呼吸。 3. 能源供需平衡：[PCr]/[Pi]比率。 现在这个比例是 被认为是代谢供给和代谢之间平衡的指标 充满活力的需求。 这将在灌注心脏中使用 扰乱稳定状态的跳跃协议。 这个程度 还将评估因缺血引起的细胞损伤而改变的平衡。 总的来说，这些基础研究将为我们提供新的见解。 正常和缺血的动态和响应生物能状态 心肌。

The overall objective of this proposal is to further define those factors in the normal and post-ischemic heart which integrate and regulate the production of high-energy phosphate compounds, namely ATP and phosphocreatine. The integration of these metabolites is viewed to be the function of the creatine kinase reaction. The net production of ATP is the consequence of mitochondrial oxidative phosphorylation. Both of these processes will be investigated in this proposal. The model is the isolated, perfused, isovolumic working rabbit heart. The analytical methodology will extensively involve the use of 31-phosphorus nuclear magnetic resonance techniques. Both kinetic and thermodynamic approaches will be employed. To this end, three specific aims have been outlined: 1. Saturation transfer and 2-D NMR studies. These biophysical techniques will be used to measure the flux rates of high-energy phosphate mediated by creatine kinase and oxidative phosphorylation in the normal and post-ischemic heart. The goal will be to determine the degree to which ischemic induced cell damage results in fundamental changes in energy production and integration. 2. In vivo respiratory control studies. Recent studies have suggested that the adenine nucleotide control of oxidative phosphorylation relates to the availability of ADP at the mitochondrial adenine nucleotide translocase. This hypothesis will be tested in vivo using pace induced changes in function to stress the myocardium in a graded manner. By assuming that the cytoplasmic form of creatine kinase is in "near-equilibrium", one can use the equilibrium constant for this reaction to calculate the free ADP content of the heart. This will then be correlated to changes in the rates of oxygen consumption, to estimate the apparent Km for ADP induced respiration. 3. Energy supply/demand balance: The [PCr]/[Pi] ratio. This ratio is now thought to be an indication of the balance between metabolic supply and energetic demand. This will be explored in the perfused heart using the pace-jump protocol to perturb the steady state. The degree to which this balance is altered by ischemic induced cell damage will also be assessed. Overall, these fundamental studies will provide new insights into the dynamic and responsive bioenergetic status of both the normal and ischemic myocardium.