USE OF STABLE ISOTOPICALLY LABELED TRACERS FOR STUDIES OF METABOLIC KINETICS

使用稳定同位素标记示踪剂进行代谢动力学研究

• 批准号: 6665928
• 负责人: BRUCE W PATTERSON
• 金额: $ 15.75万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2003-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6665928
• 关键词: biomedical resource; drug /agent; drug adverse effect; human tissue; medical rehabilitation related tag; mental disorders; rehabilitation; spectrometry; substance abuse related disorder; technology /technique; urinary tract

Studies of substrate metabolic kinetics using stable isotope labeled tracers require accurate and precise isotopic enrichment measurements. The gas chromatograph/mass spectrometer (GC/MS) is a versatile instrument for analysis of metabolic tracers but is less precise or accurate than isotope ratio mass spectrometers (IRMS). It may be inconvenient to convert target metabolites to gases (2H2, 13CO2, 15N2) analyzed by IRMS, and GC/MS permits measurements of enrichment of single components within biological mixtures. The limited accuracy and precision of GC/MS places restrictions on tracer infusion protocols, and large doses of stable isotope tracers must be infused over long periods to achieve detectable enrichment. Typically, tracer to tracee ratios (TTR) of 3-5% must be achieved. Stable isotope tracer studies could benefit from improved accuracy and precision of GC/MS measurements. We find it is possible, under carefully selected conditions, to measure very low isoto pic enrich ments (TTR 0.001-0.1%) by GC/MS. Obesity is a major US public health problem because of its increasing prevalence and causal relationship with many medical illnesses. Metabolic diseases associated with obesity and aging, such as type II diabetes mellitus, dyslipidemia, and coronary artery disease, are related to abnormalities in glucose and lipid metabolism. Body fat mass and abnormalities in glucose and lipid metabolism also increase with aging. We have evaluated independent effects of obesity and aging on fat and carbohydrate metabolism in humans in vivo using stable isotope tracers and GC/MS. By combining isotope tracer, microdialysis, and abdominal vein catheterization techniques, we developed a four-compartment model of adipose tissue glycerol kinetics. We find that fat oxidation is decreased and carbohydrate oxidation increased during moderate intensity exercise in elderly compared to young adult subjects, even though lipolysis rates were similar. These data suggest an ag ing-induced impairment in skeletal muscle fat oxidation. Exercise training normalized fat oxidation in elderly subjects. In patients with severe upper-body obesity, we find that diet-induced weight loss decreases whole body lipolytic rates. During short-term fasting, obese women exhibit blunted lipolytic and plasma insulin responses and reduced norepinephrine spillover, an index of sympathetic nervous system activity.

用稳定同位素研究底物代谢动力学 标记示踪剂需要准确和精密的同位素浓缩 测量。气相色谱/质谱仪(GC/MS)是 用于代谢示踪剂分析的多功能仪器，但较少 比同位素比质谱仪(IRMS)更精确或更准确。它 可能不方便将目标代谢物转化为气体(2H2， 13CO2，15N2)由IRMS分析，GC/MS允许测量 生物混合物中单一成分的浓缩。这个 GC/MS的精密度和准确度限制了示踪剂的使用 输注方案和大剂量稳定同位素示踪剂必须 长时间注入，以实现可检测到的浓缩。 通常，必须达到3-5%的示踪剂与被示踪物比率(TTR)。 稳定的同位素示踪研究可以受益于提高的准确性和 GC/MS测量的精密度。我们发现这是可能的，在 精心选择的条件，以测量非常低的同位素丰度 肥胖症是美国一项主要的公共健康问题 问题，因为它的患病率和因果关系不断增加 患有多种医学疾病。与以下相关的代谢性疾病 肥胖和老龄化，如II型糖尿病、血脂异常、 和冠状动脉疾病，都与血糖异常有关 和脂类代谢。体脂质量和血糖及血糖异常 随着年龄的增长，脂肪代谢也会增加。我们已经评估了 肥胖和衰老对脂肪和碳水化合物的独立影响 利用稳定同位素示踪剂和GC/MS研究人体体内代谢 通过结合同位素示踪剂、微透析和腹部静脉 插管技术，我们开发了一种四室模型 脂肪组织甘油动力学。我们发现脂肪氧化是 降低和碳水化合物氧化增加在中度 老年人的强度运动与年轻人的比较，甚至 尽管脂解率相似。这些数据表明 胰岛素引起的骨骼肌脂肪氧化损伤。锻炼 训练使老年受试者的脂肪氧化正常化。在病人中 对于严重的上半身肥胖症，我们发现饮食导致体重减轻 降低全身脂解率。在短期禁食期间， 肥胖女性表现出迟钝的脂解和血浆胰岛素反应， 去甲肾上腺素溢出减少，这是交感神经紧张的一个指标 系统活动。