REGULATION OF HEART HIGH-ENERGY PHOSPHATE METABOLISM

本提案的总体目标是进一步界定这些因素 在正常和缺血后的心脏中， 生产高能磷酸盐化合物，即ATP， 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的净产量是 线粒体氧化磷酸化的结果。 这两 本提案将对工艺进行研究。 模型是 离体灌注等容工作兔心脏。 分析 该方法将广泛涉及使用31-磷核 磁共振技术。 动力学和热力学方法 将被雇用。 为此，提出了三个具体目标： 1.饱和转移和2-D NMR研究。 这些生物物理技术 将被用来测量高能磷酸盐的通量率介导的 肌酸激酶和氧化磷酸化在正常和 缺血后心脏 我们的目标是确定 局部缺血诱导的细胞损伤导致能量的根本变化 生产和整合。 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的可用性。 该假设将使用起搏诱导的变化在体内进行测试， 以分级方式对心肌施加应力。 通过假设 肌酸激酶的细胞质形式处于“接近平衡”，可以使用 该反应的平衡常数，以计算游离ADP 心的内容。 这将与利率的变化相关， 氧消耗量，以估计ADP诱导的表观Km 呼吸 3.能源供应/需求平衡：[PCr]/[Pi]比率。 这个比例现在 这被认为是代谢供应和 有活力的需求。 这将在灌注的心脏中使用 起搏跳跃协议来扰乱稳定状态 这种程度 还将评估由局部缺血诱导的细胞损伤改变的平衡。 总的来说，这些基础研究将提供新的见解， 正常和缺血的动态和响应性生物能量状态 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.