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J Biol Chem. 2016 Sep 2;291(36):19031-41. doi: 10.1074/jbc.M116.742262. Epub 2016 Jul 18.

An Oral Load of [13C3]Glycerol and Blood NMR Analysis Detect Fatty Acid Esterification, Pentose Phosphate Pathway, and Glycerol Metabolism through the Tricarboxylic Acid Cycle in Human Liver.

Author information

1
From the Advanced Imaging Research Center and the Departments of Internal Medicine and eunsook.jin@utsouthwestern.edu.
2
From the Advanced Imaging Research Center and Radiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, the Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080, and.
3
From the Advanced Imaging Research Center and the Departments of Internal Medicine and Radiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, the VA North Texas Health Care System, Dallas, Texas 75216.

Abstract

Drugs and other interventions for high impact hepatic diseases often target biochemical pathways such as gluconeogenesis, lipogenesis, or the metabolic response to oxidative stress. However, traditional liver function tests do not provide quantitative data about these pathways. In this study, we developed a simple method to evaluate these processes by NMR analysis of plasma metabolites. Healthy subjects ingested [U-(13)C3]glycerol, and blood was drawn at multiple times. Each subject completed three visits under differing nutritional states. High resolution (13)C NMR spectra of plasma triacylglycerols and glucose provided new insights into a number of hepatic processes including fatty acid esterification, the pentose phosphate pathway, and gluconeogenesis through the tricarboxylic acid cycle. Fasting stimulated pentose phosphate pathway activity and metabolism of [U-(13)C3]glycerol in the tricarboxylic acid cycle prior to gluconeogenesis or glyceroneogenesis. Fatty acid esterification was transient in the fasted state but continuous under fed conditions. We conclude that a simple NMR analysis of blood metabolites provides an important biomarker of pentose phosphate pathway activity, triacylglycerol synthesis, and flux through anaplerotic pathways in mitochondria of human liver.

KEYWORDS:

anaplerosis; biomarker; gluconeogenesis; glycerol; liver metabolism; mitochondria; pentose phosphate pathway (PPP); tricarboxylic acid cycle (TCA cycle) (Krebs cycle); triglyceride

PMID:
27432878
PMCID:
PMC5009274
DOI:
10.1074/jbc.M116.742262
[Indexed for MEDLINE]
Free PMC Article

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