IN VIVO NMR STUDIES OF CARBOHYDRATE METABOLISM

碳水化合物代谢的体内核磁共振研究

• 批准号: 2141522
• 负责人: GERALD I SHULMAN
• 金额: $ 22.65万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-12-01 至 1998-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2141522
• 关键词: acetaminophen; biological models; carbohydrate metabolism; carbon; cell type; chemical conjugate; denervation; dogs; glycogen; glycogenesis; glycolysis; laboratory rat; liver cells; liver metabolism; mass spectrometry; nuclear magnetic resonance spectroscopy; pyruvate carboxylase; pyruvate kinase; stable isotope; uridine diphosphate glucose

Glycogen synthesis is quantitatively one of the most important fates of a glucose load and defects in glycogen synthesis have been demonstrated to be quantitatively the most important factor contributing to glucose intolerance in the Non Insulin Dependent Diabetes Mellitus. This project continues studies on the hormonal and substrate regulation of hepatic glycogen synthesis in vivo using both nuclear magnetic resonance spectroscopy (NMR) and gas chromatography-mass spectrometry (GC-MS) techniques. The specific questions that will be addressed are: (l) Whether or not there is functional heterogeneity in regards to glucose and glycogen metabolism in periportal versus perivenous hepatocytes in vivo using the dual digitonin pulse technique. (2) To validate 13C NMR measurements of hepatic glycogen concentration in vivo as well to validate acetaminophen as a noninvasive probe to assess fluxes of the direct and indirect pathways of hepatic glycogen synthesis in vivo. Both will be done by direct biochemical comparison with 13C NMR tissue measurements. (3) To develop a method to assess pyruvate kinase flux relative to pyruvate carboxylase flux in vivo and then to apply this technique to examine the regulation of this substrate cycle acutely by glucagon, epinephrine and chronically by triiodothyronine. (4) To assess the roles of glucose and insulin in regulating hepatic glycogen turnover in vivo as well as address the question of whether or not the last glycogen molecule synthesized is the first molecule degraded and (5) To assess net intrahepatic flux of substrate through the direct and indirect pathways of hepatic glycogen synthesis as well as flux through pyruvate dehydrogenase, pyruvate carboxylase and fumarase by performing computer modeling of the 13C labeling patterns in intrahepatic metabolites obtained from hepatically catheterized conscious dogs to examine: i) The effect of hepatic denervation on these pathways and ii) The effect of hypercortisolemia on these pathways. Overall, these studies will validate novel noninvasive methods for studying liver glycogen metabolism in humans and provide new insights into the regulation of liver glycogen synthesis, glycogen turnover and mechanisms by which hepatic glycogen is degraded. Such data are important for understanding the pathogenesis of glucose intolerance in Non Insulin Dependent Mellitus.

糖原合成是定量的最重要的命运之一 已经证明了糖原合成中的葡萄糖负荷和缺陷 定量造成葡萄糖的最重要因素 在非胰岛素依赖性糖尿病中不耐受。 这个项目 继续研究肝的激素和底物调节 使用两个核磁共振在体内糖原合成 光谱法（NMR）和气相色谱质量光谱法（GC-MS） 技术。将要解决的具体问题是：（l） 在葡萄糖方面是否有功能异质性 和糖原代谢中的外周与细胞肝细胞中的代谢 使用双digitonin脉冲技术的体内。 （2）验证13C NMR 在体内测量肝糖原浓度也 验证对乙酰氨基酚是一种无创探针，以评估 体内肝糖原合成的直接和间接途径。 两个都 将通过与13C NMR组织的直接生化比较来完成 测量。 （3）开发一种评估丙酮酸激酶通量的方法 相对于丙酮酸羧化酶在体内的通量，然后应用 通过急性检查该底物周期调节的技术 胰高血糖素，肾上腺素和三碘甲状腺素长期。 （4）评估 葡萄糖和胰岛素在调节肝糖原更新中的作用 体内以及解决最后一个问题的问题 合成的糖原分子是第一个分子降解，（5）至 通过直接和间接评估底物的肝内通量 肝糖原合成的途径以及通过丙酮酸的通量 通过执行计算机，脱氢酶，丙酮酸羧化酶和富马酶 在肝内代谢物中的13C标记模式的建模 从肝导管意识型狗中获得的检查：i） 肝神经对这些途径的影响和ii） 这些途径上的高皮质血症。 总体而言，这些研究将 验证用于研究肝糖原代谢的新型无创方法 在人类中，并提供有关肝糖原调节的新见解 合成，糖原更新和肝糖原的机制 退化。 这样的数据对于理解的发病机理很重要 非胰岛素依赖性梅洛氏菌中的葡萄糖不耐症。