Integration of [U-13C]glucose and 2H2O for quantification of hepatic glucose pr...

• Author(s): Perdigoto, Rui ; Rodrigues, Tiago B. ; Furtado, Alexandre L. ; Porto, Armando ; Geraldes, Carlos F. G. C. ; Jones, John G.
• Date: 2003
• Persistent ID: http://hdl.handle.net/10316/8430
• Origin: Estudo Geral - Universidade de Coimbra
• Document Type: Article
• Language: English

Description

Glucose metabolism in five healthy subjects fasted for 16 h was measured with a combination of [U-13C]glucose and 2H2O tracers. Phenylbutyric acid was also provided to sample hepatic glutamine for the presence of 13C-isotopomers derived from the incorporation of [U-13C]glucose products into the hepatic Krebs cycle. Glucose production (GP) was quantified by 13C NMR analysis of the monoacetone derivative of plasma glucose following a primed infusion of [U-13C]glucose and provided reasonable estimates (1.90 ± 0.19 mg/kg/min with a range of 1.60-2.15 mg/kg/min). The same derivative yielded measurements of plasma glucose 2H-enrichment from 2H2O by 2H NMR from which the contribution of glycogenolytic and gluconeogenic fluxes to GP was obtained (0.87 ± 0.14 and 1.03 ± 0.10 mg/kg/min, respectively). Hepatic glutamine 13C-isotopomers representing multiply-enriched oxaloacetate and [U-13C]acetyl-CoA were identified as multiplets in the 13C NMR signals of the glutamine moiety of urinary phenylacetylglutamine, demonstrating entry of the [U-13C]glucose tracer into both oxidative and anaplerotic pathways of the hepatic Krebs cycle. These isotopomers contributed 0.1-0.2% excess enrichment to carbons 2 and 3 and sim0.05% to carbon 4 of glutamine. Copyright © 2003 John Wiley & Sons, Ltd. http://dx.doi.org/10.1002/nbm.826