RENAL AMMONIAGENESIS: 15NH3 STUDIES WITH GC-MS

这项建议需要对 控制肾脏氨基酸代谢的机制(S)， 不同酸碱状态下的氨化和糖异生作用。 这项工作将涉及五个主要主题：(1)代谢 在酸中毒中启动增强的氨化作用的信号；(2) 合成氨的限速代谢途径(S)； 氨化作用的效应物和/或抑制物在 基础生物化学；(4)假定的关系 肾脏氨和葡萄糖的形成；(5)生化 在诱导期和恢复期发生的适应 由酸中毒和碱中毒引起。这项工作的核心假设是 通过柠檬酸合成酶途径减少的通量是一种 一系列协调一致的事件中的第一步，导致 酸中毒的产氨率增加。一个推论 假说是α-酮戊二酸库的减少 次要的是通过柠檬酸合成酶减少的通量 伴随着谷氨酸脱氢酶增强的通量 谷氨酸氧化脱氨基的释放 NH3。我们还将探索这种增强的可能性 酸中毒中的氨化和糖异生作用是(或不是) 共同代谢信号作用下的相互依赖现象 和对照，葡萄糖产量的增加提供了 谷氨酸碳的出口。通量减少的意义 通过谷氨酰胺合成酶反应教唆HN3 还将研究生产情况。 这些主题将通过孵育分离的大鼠肾脏来检验 存在15N和/或13C标记前体的小管 以及缺乏代谢调节剂和/或抑制剂。 重要前体产品的后续测定 将使用气体建立关系和流量 色质联用和/或核磁 共振光谱学。这样获得的数据将是科学的 通过深化我们对肾氨生成的认识来进口 对氢离子动态平衡扰动的反应。这个 项目将根据以下阶段对这种适应进行评估 酸中毒或碱中毒，即在诱发或恢复期间 两个州都行。

This proposal entails a comprehensive examination of the mechanism(s) controlling renal amino acid metabolism, ammoniagenesis and gluconeogenesis in various acid base states. The work will address five primary themes: (1) the metabolic signals initiating augmented ammoniagenesis in acidosis; (2) the rate limiting metabolic pathway(s) for ammonia production; (3) the role of effectors and/or inhibitors of ammoniagenesis on the underlying biochemistry; (4) the putative relationship between renal ammonia and glucose formation; (5) the biochemical adaptation occurring both during the induction of and recovery from acidosis and alkalosis. The core hypothesis of the work is that diminished flux through the citrate synthetase pathway is an initial step in a coordinated sequence of events leading to an increased rate of ammoniagenesis in acidosis. A corollary hypothesis is that the diminution of the alpha-ketoglutarate pool secondary to reduced flux through citrate synthetase is accompanied by enhanced flux through glutamate dehydrogenase toward oxidative deamination of glutamate with the release of NH3. We also will explore the possibility that the augmentation of ammoniagenesis and gluconeogenesis in acidosis are (or are not) inter-dependent phenomenon subject to common metabolic signals and controls, with the increase of glucose production providing an outlet for glutamate carbon. The significance of diminished flux through the glutamine synthetase reaction in abetting HN3 production will be studied as well. These topics will examined by incubating isolated rat renal tubules with 15N and/or 13C labelled precursors in the presence and absence of metabolic modulators and/or inhibitors. Subsequent determination of important precursor-product relationships and flux rates will be made using gas chromatography-mass spectrometry and/or nuclear magnetic resonance spectroscopy. The data so obtained will be of scientific import by deepening our understanding of renal ammoniagenesis in response to perturbations of hydrogen ion homeostasis. The project will evaluate such adaptations in terms of the stage of acidosis or alkalosis, i.e., during the induction of or recovery from either state.