A limitation in the use of mass isotopomer distributions to measure gluconeogenesis in fasting humans.
A limitation in the use of mass isotopomer distributions to measure gluconeogenesis in fasting humans.
复制标题
使用质量同位素异构体分布来测量禁食人类的糖异生作用的限制。
DOI：
10.1152/ajpendo.1995.269.1.e18
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Brunengraber,H
中科院分区：
文献类型：
--
作者：
Landau,BR;Fernandez,CA;Previs,SF;Ekberg,K;Chandramouli,V;Wahren,J;Kalhan,SC;Brunengraber,H
使用的质量同位素在葡萄糖中的分布从[U-13 C]甘油估计分数率的异构体进行了检查。[U-13 C]甘油输注给摄入对乙酰氨基酚并禁食60 h的正常受试者。通过质谱法测定血糖和尿对乙酰氨基酚葡萄糖醛酸苷中葡萄糖醛酸的同位素分布。该分布与仅通过磷酸丙糖的单一池的异源生成来生产葡萄糖是不相容的。相反，在假设单一富集的磷酸丙糖池的情况下，分布表明，尽管禁食60小时，但来自未标记葡萄糖源的葡萄糖形成量与来自该池的葡萄糖形成量大致相同。因此，数据表明甘油代谢的细胞异质性，因此两个或多个富集程度显著不同的合并液是葡萄糖和葡萄糖醛酸的来源。这种异质性与门静脉周围的甘油浓度远高于肝小叶中央周围区的甘油浓度有关。除了异质性的证据，研究结果强调了在应用质量同位素分布的分析来测量聚合物生物合成的前体池中存在的异质性的限制。
The use of distributions of mass isotopomers in glucose from [U-13C]glycerol to estimate fractional rates of gluconeogenesis was examined. [U-13C]glycerol was infused into normal subjects who ingested acetaminophen and fasted for 60 h. Isotopomer distributions were measured by mass spectrometry in blood glucose and in glucuronic acid from urinary acetaminophen glucuronide. The distributions are incompatible with glucose production solely via gluconeogenesis from a single pool of triose phosphates. Rather, with the assumption of a single enriched triose phosphate pool, the distributions indicate, despite the 60 h of fasting, about as much glucose formation from an unlabeled glucose source as from that pool. Therefore the data indicate cellular heterogeneity in glycerol's metabolism, so that two or more pools with significantly different enrichments were the source of the glucose and glucuronic acid. This heterogeneity is related to much greater concentrations of glycerol in periportal than in pericentral zones of the liver lobule. Beyond evidence for heterogeneity, the findings emphasize a limitation in applying analyses of mass isotopomer distributions to measure polymer biosynthesis in the presence of heterogeneity in the precursor pool.