Perry Rachel J, Peng Liang, Cline Gary W, Butrico Gina M, Wang Yongliang, Zhang Xian-Man, Rothman Douglas L, Petersen Kitt Falk, Shulman Gerald I
Departments of Internal Medicine, Yale University School of Medicine, New Haven, CT, 06520, USA.
Departments of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, 06520, USA.
Nat Commun. 2017 Oct 6;8(1):798. doi: 10.1038/s41467-017-01143-w.
Hepatic mitochondria play a central role in the regulation of intermediary metabolism and maintenance of normoglycemia, and there is great interest in assessing rates of hepatic mitochondrial citrate synthase flux (V ) and pyruvate carboxylase flux (V ) in vivo. Here, we show that a positional isotopomer NMR tracer analysis (PINTA) method can be used to non-invasively assess rates of V and V fluxes using a combined NMR/gas chromatography-mass spectrometry analysis of plasma following infusion of [3-C]lactate and glucose tracer. PINTA measures V and V fluxes over a wide range of physiological conditions with minimal pyruvate cycling and detects increased hepatic V following treatment with a liver-targeted mitochondrial uncoupler. Finally, validation studies in humans demonstrate that the V /V ratio measured by PINTA is similar to that determined by in vivo NMR spectroscopy. This method will provide investigators with a relatively simple tool to non-invasively examine the role of altered hepatic mitochondrial metabolism.Liver mitochondrial metabolism plays an important role for glucose and lipid homeostasis and its alterations contribute to metabolic disorders, including fatty liver and diabetes. Here Perry et al. develop a method for the measurement of hepatic fluxes by using lactate and glucose tracers in combination with NMR spectroscopy.
肝线粒体在中间代谢调节和维持正常血糖水平中起核心作用，因此人们对评估体内肝线粒体柠檬酸合酶通量（V）和丙酮酸羧化酶通量（V）的速率非常感兴趣。在此，我们表明，在输注[3-C]乳酸和葡萄糖示踪剂后，通过对血浆进行核磁共振/气相色谱-质谱联用分析，一种位置同位素体核磁共振示踪分析（PINTA）方法可用于非侵入性评估V和V通量的速率。PINTA在广泛的生理条件下测量V和V通量，丙酮酸循环极少，并检测到用肝脏靶向线粒体解偶联剂处理后肝脏V增加。最后，在人体中的验证研究表明，PINTA测量的V/V比值与体内核磁共振波谱法测定的比值相似。该方法将为研究人员提供一个相对简单的工具，用于非侵入性地研究肝线粒体代谢改变的作用。肝线粒体代谢对葡萄糖和脂质稳态起着重要作用，其改变会导致包括脂肪肝和糖尿病在内的代谢紊乱。在此，佩里等人开发了一种结合使用乳酸和葡萄糖示踪剂以及核磁共振波谱法来测量肝通量的方法。
