REGULATORY MECHANISMS IN KETOGENESIS AND GLUCONEOGENESIS

该提案概述了我们的实验方法，以三个重要的 涉及肝脏代谢的调节问题。 其中第一个 这些问题涉及到如何描述 由线粒体介导的生酮和生酮途径 单羧酸转运蛋白 我们建议， 线粒体乙酰乙酸通过单羧酸转化为胞浆丙酮酸 转运子是供应前体的主要调节器， 致炎途径。 提出了几个实验来测试和 在各种肝脏衍生的代谢系统中详细阐述这一假设。 将在开发特异性抑制剂方面作出相当大的努力 单羧酸转运蛋白的最终目的是分离和 描述了这个重要的线粒体的分子特性 基板输送系统。 第二，我们建议进行研究， α-肾上腺素能激动剂的调节作用的某些方面， 就像肝脏里的肾上腺素一样 实验已经提出a）定义 释放到肝细胞质中的钙离子的来源 和B）表征以下物质的作用： 对各种线粒体过程的α-肾上腺素能刺激。 最后， 肝甘氨酸裂解系统的调节特性将是 在灌注的大鼠肝脏和分离的肝脏线粒体中研究。 各种替代底物（例如， 脂肪酸、氨基酸和酮体）和核苷酸种类（例如， 腺嘌呤和吡啶核苷酸）。 可能的抑制 几种化合物对线粒体甘氨酸转运的影响将是 评估。 甘氨酸裂解系统的变化将在 来自处于几种营养/激素状态的动物的肝脏（例如， 进食的、空腹的糖尿病患者等）。 最后，我们想定义 甘氨酸合成酶多酶活性与 复杂的肝脏和各种临床定义的高甘氨酸血症状态。

This proposal outlines our experimental approach to three important regulatory problems involved in liver metabolism. The first of these problems concerns the characterization of a regulatory relationship between the ketogenic and gluconeogenic pathways mediated by the mitochondrial monocarboxylate translocator. We have proposed that the exchange of mitochondrial acetoacetate for cytosolic pyruvate via the monocarboxylate translocator is a primary regulator of the supply of precursors for the gluconeogenic pathway. Several experiments are proposed to test and to elaborate upon this hypothesis in various liver-derived metabolic systems. Considerable effort will be given to the development of specific inhibitors of the monocarboxylate translocator with an ultimate goal of isolating and characterizing the molecular properties of this important mitochondrial substrate transport system. Second, we have proposed studies to define certain aspects of the regulatory effects of Alpha-adrenergic agonists such as epinephrine in the liver. Experiments have been suggested a) to define the source of the calcium ions which are released into the liver cytosol upon Alpha-stimulation and b) to characterize the effects of Alpha-adrenergic stimulation on various mitochondrial processes. Finally, the regulatory properties of the hepatic glycine cleavage system will be investigated in perfused rat livers and in isolated liver mitochondria. The possible regulatory effects of various alternative substrates (e.g., fatty acids, amino acids and ketone bodies) and nucleotide species (e.g., adenine and pyridine nucleotides) will be assessed. Possible inhibitory effects of several compounds on mitochondrial glycine transport will be evaluated. Changes in the glycine cleavage system will be monitored in livers derived from animals in several nutritional/hormonal state (e.g., fed, fasted diabetic, etc.). Ultimately we would like to define the relationship between the activity of the glycine synthase multienzyme complex in the liver and various clinically defined hyperglycinemic states.