Propionate Increases Hepatic Pyruvate Cycling and Anaplerosis and Alters Mitochondrial Metabolism.
Propionate Increases Hepatic Pyruvate Cycling and Anaplerosis and Alters Mitochondrial Metabolism.
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DOI：
10.1074/jbc.m116.720631
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发表时间：
2016-06-03
期刊：
影响因子：
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通讯作者：
Shulman GI
中科院分区：
文献类型：
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作者：
Perry RJ;Borders CB;Cline GW;Zhang XM;Alves TC;Petersen KF;Rothman DL;Kibbey RG;Shulman GI
在哺乳动物中，丙酮酸激酶（PK）在调节糖酵解和代谢之间的平衡中起着关键作用;然而，体内代谢激素和底物对PK通量的调节知之甚少。为此，我们开发了一种新的NMR-液相色谱/串联质谱（LC-MS/MS）方法，使用[3- 13 C]乳酸作为示踪剂，在体内直接评估丙酮酸循环相对于线粒体丙酮酸代谢（VPyr-Cyc/VMito）。使用这种方法，在禁食过夜的大鼠中，VPyr-Cyc/VMito仅为6%。相比之下，当以先前用作示踪剂的剂量同时输注丙酸盐时，其使VPyr-Cyc/VMito增加20-30倍，使肝TCA代谢物浓度增加2-3倍，并使内源性葡萄糖产生速率增加20- 100%。生理刺激，胰高血糖素和肾上腺素，都增加肝葡萄糖的生产，但只有胰高血糖素抑制VPyr-Cyc/VMito。这些数据表明，在禁食条件下，当肝糖原异生被刺激时，与VMito通量相比，丙酮酸再循环在肝脏中相对较低，并且肝脏代谢，特别是丙酮酸循环，对丙酸敏感，使其成为评估体内肝糖酵解、糖原异生和线粒体代谢的不合适的示踪剂。
In mammals, pyruvate kinase (PK) plays a key role in regulating the balance between glycolysis and gluconeogenesis; however, in vivo regulation of PK flux by gluconeogenic hormones and substrates is poorly understood. To this end, we developed a novel NMR-liquid chromatography/tandem-mass spectrometry (LC-MS/MS) method to directly assess pyruvate cycling relative to mitochondrial pyruvate metabolism (VPyr-Cyc/VMito) in vivo using [3-13C]lactate as a tracer. Using this approach, VPyr-Cyc/VMito was only 6% in overnight fasted rats. In contrast, when propionate was infused simultaneously at doses previously used as a tracer, it increased VPyr-Cyc/VMito by 20–30-fold, increased hepatic TCA metabolite concentrations 2–3-fold, and increased endogenous glucose production rates by 20–100%. The physiologic stimuli, glucagon and epinephrine, both increased hepatic glucose production, but only glucagon suppressed VPyr-Cyc/VMito. These data show that under fasting conditions, when hepatic gluconeogenesis is stimulated, pyruvate recycling is relatively low in liver compared with VMito flux and that liver metabolism, in particular pyruvate cycling, is sensitive to propionate making it an unsuitable tracer to assess hepatic glycolytic, gluconeogenic, and mitochondrial metabolism in vivo.