[13C] GC-C-IRMS analysis of methylboronic acid derivatives of glucose from liver glycogen after the ingestion of [13C] labeled tracers in rats.
We developed a complete method to measure low [(13)C] enrichments in glycogen. Fourteen rats were fed a control diet. Six of them also ingested either [U-(13)C] glucose (n=2) or a mixture of 20 [U-(13)C] amino acids (n=4). Hepatic glycogen was extracted, digested to glucose and purified on anion-cation exchange resins. After the optimization of methylboronic acid derivatization using GC-MS, [(13)C] enrichment of extracted glucose was measured by GC-C-IRMS. The accuracy was addressed by measuring the enrichment excess of a calibration curve, which observed values were in good agreement with the expected values (R=0.9979). Corrected delta values were -15.6+/-1.6 delta(13)C (per thousand) for control rats (n=8) and increased to -5 to 8 delta(13)C (per thousand) per thousand and 12-14 delta(13)C (per thousand) per thousand after the ingestion of [U-(13)C] amino acids or [U-(13)C] glucose as oral tracers, respectively. The method enabled the determination of dietary substrate transfer into glycogen. The sequestration of dietary glucose in liver glycogen 4 h after the meal was 35% of the ingested dose whereas the transfer of carbon skeletons from amino acids was only 0.25 to 1%.
INRA, CNRH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, F-75005 Paris, France.
Catherine
C
Luengo
Dalila
D
Azzout-Marniche
Claire
C
Fromentin
Julien
J
Piedcoq
Sophie
S
Lemosquet
Daniel
D
Tomé
Claire
C
Gaudichon
D000818:Animals; D001896:Boron Compounds / Q000737:chemistry*; D002247:Carbon Isotopes / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D005947:Glucose / Q000737:chemistry*; D008112:Liver Glycogen / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D015394:Molecular Structure; D051381:Rats; D017208:Rats, Wistar
D001896:Boron Compounds; D002247:Carbon Isotopes; D008112:Liver Glycogen; C116999:methaneboronic acid; D005947:Glucose