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: 6486808
• 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: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2002-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6486808
• 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.

利用稳定同位素研究底物代谢动力学 标记的示踪剂需要准确和精确的同位素富集 测量. 气相色谱/质谱仪（GC/MS）是一种 用于分析代谢示踪剂的多功能仪器，但较少 比同位素比质谱仪（IRMS）更精确或准确。 它 可能不便于将目标代谢物转化为气体（2 H2， 13 CO2，15 N2），GC/MS允许测量 生物混合物中单一组分的富集。 的 GC/MS有限的准确度和精密度限制了示踪剂 输注方案和大剂量的稳定同位素示踪剂必须 长时间注入以达到可检测的浓缩。 通常，示踪剂与示踪剂的比率（TTR）必须达到3-5%。 稳定同位素示踪剂研究可以受益于提高准确性， GC/MS测量的精确度。 我们发现，在 精心选择的条件，以测量非常低的同位素富集 通过GC/MS测定的总胆固醇（TTR 0.001-0.1%）。 问题，因为它的日益普遍和因果关系 许多医学疾病。 代谢性疾病与 肥胖和衰老，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 和脂质代谢。 身体脂肪量和血糖异常， 脂质代谢也随年龄增长而增加。 我们已经评估 肥胖和衰老对脂肪和碳水化合物的独立影响 使用稳定同位素示踪剂和GC/MS在人体内进行代谢。 结合同位素示踪、微透析和腹静脉 导管插入技术，我们开发了一个四室模型， 脂肪组织甘油动力学。 我们发现脂肪氧化 减少和碳水化合物氧化增加， 老年人与年轻人相比， 尽管脂解率相似。 这些数据表明， 饮食诱导的骨骼肌脂肪氧化损伤。 行使 训练使老年人的脂肪氧化正常化。 患者 对于严重的上半身肥胖，我们发现饮食引起的体重减轻 降低全身脂肪分解率。 在短期禁食期间， 肥胖妇女表现出迟钝的脂解和血浆胰岛素反应， 减少去甲肾上腺素溢出，这是一种交感神经 系统活动。