IMPROVED GLUCONEOGENESIS ESTIMATES FROM LABELED CARBON

在评估人的代谢状况时， 实验动物没有测量比 再生速率 然而，可靠的测量方法 这一重要指标目前尚不具备。 一个共同 实验程序是给动物注射 葡萄糖的放射性标记的碳前体（例如，丙氨酸）和 测量葡萄糖中放射性标记的出现率。 这 方法需要同位素稀释的校正因子，因为 放射性标记的碳移动到葡萄糖。 的目的 建议的研究是开发改进的方法， 从标记碳中再生。 碳的路径从 葡萄糖的代谢前体，乳酸盐或丙氨酸， 复杂，因为促炎途径与 TCA循环。 为了提供一个框架来分析这个复杂的 互动，我已经制定了一个全面的数学 TCA循环流量和土壤自生的模式。 拟议工作 将在建模过程中建立的关系应用于 一个实际的医学上重要的问题 的四项具体 本项目的目的是：（1）确定草酰乙酸是否 池在体内肝细胞中是均匀的。 (2)评价 常用的假设是示踪剂的稀释度在 草酰乙酸不被刺激的过程改变， 以及谷氨酰胺流入TCA循环 并不重要。 3)为了评估一种新的方法， 基于建模方法I确定同位素稀释 已经发展。 (4)为了确定蛋白酸羧化酶， 在胚胎发生的第一步，可以在体内使用 14CO2比率方程的修改形式，其中尿素碳 替代CO2并反映肝脏14CO2的产生。 到 为实现这些具体目标，将开展研究， 使用分离的大鼠肝细胞以及完整的动物 （大鼠）。 该项目的长期目标是改善 了解人类肝脏碳代谢。

In the assessment of the metabolic status of man and experimental animal no measurement is more fundamental than the rate of gluconeogenesis. Yet, reliable methods for measuring this important indicator are not available. A common experimental procedure is to inject an animal with a radiolabeled carbon precursor of glucose (e.g., alanine) and measure the rate of appearance of radiolabel in glucose. This method requires a correction factor for isotope dilution as the radiolabeled carbon travels to glucose. The objective of the proposed research is to develop improved methods for estimating gluconeogenesis from labeled carbon. The path of carbon from gluconeogenic precursors, lactate or alanine, to glucose is complex because the gluconeogenic pathway interacts with the TCA cycle. To provide a framework for analyzing this complex interaction, I have developed a comprehensive mathematical model of TCA cycle flux and gluconeogenesis. The proposed work will apply relationships developed in this modeling process to a practical, medically important problem. The four specific aims of the project are: (1) To determine if the oxaloacetate pool is homogeneous in hepatic cells in vivo. (2) To evaluate the commonly used assumptions that the dilution of tracer at oxaloacetate is not changed by processes which stimulate gluconeogenesis, and that flux of glutamine into the TCA cycle is not significant. 3) To evaluate a new method for determining isotope dilution based on the modeling approach I have developed. (4) To determine if pryuvate carboxylase, the first step in gluconeogenesis, can be evaluated in vivo using a modified form of the 14Co2 ratios equation where urea carbon substitutes for CO2 and reflects hepatic 14CO2 production. To accomplish these specific aims studies will be carried out using isolated rat hepatocytes as well as intact animals (rats). The long term goal of this project is to improve the understanding of human hepatic carbon metabolism.