Isotopomics: A Top-Down Systems Biology Approach for Understanding Dynamic Metabolism in Rats Using [1,2-13C2] Acetate

• Published in: Analytical chemistry (Washington) 2010-01, Vol.82 (2), p.646-653
• Main Authors: Godin, Jean-Philippe, Ross, Alastair B, Rezzi, Serge, Poussin, Carine, Martin, Francois-Pierre, Fuerholz, Andreas, Cléroux, Marilyn, Mermoud, Anne-France, Tornier, Lionel, Arce Vera, Francia, Pouteau, Etienne, Ramadan, Ziad, Kochhar, Sunil, Fay, Laurent-Bernard
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Animals; Carbon Isotopes - metabolism; Chemistry; Chromatographic methods and physical methods associated with chromatography; Exact sciences and technology; Gas chromatographic methods; Gas Chromatography-Mass Spectrometry - methods; Ion chromatography; Isotopes; Kinetics; Magnetic Resonance Spectroscopy - methods; Male; Mass spectrometry; Metabolism; Metabolomics; Multivariate Analysis; NMR; Nuclear magnetic resonance; Rats; Rodents; Sodium Acetate - blood; Sodium Acetate - metabolism; Spectrometric and optical methods; Time Factors
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac902086g

Isotope labeled tracers are commonly used to quantify the turnover rates of various metabolic intermediates and yield information regarding physiological regulation. Studies often only consider either one nutritional state (fasted or fed) and/or one question (e.g., measure of lipid or protein turnover). In this article, we consider a novel application combining the global approach of metabonomics with widespread stable isotope labeling as a way of being able to map metabolism in open mammalian systems, an approach we call “isotopomics”. A total of 45 15-week-old male Zucker rats were administrated different amounts (from 0.5 to 8 mmol/kg) of sodium [1,2-13C2] acetate. Plasma samples taken at 1, 4, and 24 h were analyzed with 13C nuclear magnetic resonance (NMR) and gas chromatography/mass spectrometry (GC/MS) to measure 13C isotopic enrichment of 39 plasma metabolites across a wide range of compound classes (amino acids, short-chain fatty acids, lactate, glucose, and free fatty acids). Isotopic enrichment from 0.1−7.1 mole percent excess (MPE) for the highest dose could be reliably measured in 16 metabolites, and the kinetics of their 13C isotopic enrichment are reported. Clustering metabolites based on 13C kinetic curves enabled highlighting of time dependent patterns of 13C distribution through the key metabolic pathways. These kinetic and quantitative data were reported into a biochemical map. This type of isotopomic approach for mapping dynamic metabolism in an open system has great potential for advancing our mechanistic knowledge of how different interventions and diseases can impact the metabolic response of animals and humans.