Isotopic discrimination between D-[1-(13)C]fructose and D-[2-(13)C]fructose in rat liver cells.
When liver cells from either normal or hereditarily diabetic rats are exposed to (13)C-enriched D-fructose (10 mM) and unlabelled D-glucose (also 10 mM) in the presence of D(2)O, the output of (13)C-enriched D-glucose generated from D-[1-(13)C]fructose is significantly lower than that from D-[2-(13)C]fructose. This coincides with a higher generation of (13)C-enriched L-lactate and L-alanine from D-[1-(13)C]fructose, as compared to D-[2-(13)C]fructose. In absolute terms, the mean paired difference in the output of (13)C-enriched D-glucose generated from D-[1-(13)C]fructose versus D-[2-(13)C]fructose is not significantly different from the mean paired difference in the production of (13)C-enriched L-lactate and L-alanine from the same precursors, with an overall mean value of 7.01 +/- 1.59 micromol (n = 8; P < 0.005). It is proposed that these findings indicate isotopic discrimination at the phosphoglucoisomerase level between (12)C and (13)C for the carbon atom in position 1 (as compared to that in position 2) of D-fructose 6-phosphate.
Malaisse
Willy J
WJ
Laboratory of Experimental Hormonology (Université Libre de Bruxelles) and High Resolution NMR Center (Vrije Universiteit Brussel), Brussels Free Universities, Brussels, Belgium. malaisse@ulb.ac.be
Willem
Rudolph
R
D000409:Alanine / Q000378:metabolism; D000818:Animals; D002247:Carbon Isotopes; D002469:Cell Separation; D003903:Deuterium / Q000737:chemistry; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D005632:Fructose / Q000378:metabolism* / Q000493:pharmacokinetics*; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D017208:Rats, Wistar
D002247:Carbon Isotopes; D005632:Fructose; D019344:Lactic Acid; D003903:Deuterium; D005947:Glucose; D000409:Alanine