Article révisé par les pairs
Résumé : When liver cells from either normal or hereditarily diabetic rats are exposed to 13C-enriched D-fructose (10 mM) and unlabelled D-glucose (also 10 mM) in the presence of D2O, the output of 13C-enriched D-glucose generated from D-[1-13C]fructose is significantly lower than that from D-[2-13C]fructose. This coincides with a higher generation of 13C-enriched L-lactate and L-alanine from D-[1-13C]fructose, as compared to D-[2- 13C]fructose. In absolute terms, the mean paired difference in the output of 13C-enriched D-glucose generated from D-[1- 13C]fructose versus D-[2-13C]fructose is not significantly different from the mean paired difference in the production of 13C-enriched L-lactate and L-alanine from the same precursors, with an overall mean value of 7.01 ± 1.59 μmol (n = 8; P < 0.005). It is proposed that these findings indicate isotopic discrimination at the phosphoglucoisomerase level between 12C and 13C for the carbon atom in position 1 (as compared to that in position 2) of D-fructose 6-phosphate. © 2003 Elsevier SAS. All rights reserved.