Hepatic UDP-glucose 13C isotopomers from [U-13C]glucose: a simple analysis by 13C NMR of urinary menthol glucuronide.
Menthol glucuronide was isolated from the urine of a healthy 70-kg female subject following ingestion of 400 mg of peppermint oil and 6 g of 99% [U-(13)C]glucose. Glucuronide (13)C-excess enrichment levels were 4-6% and thus provided high signal-to-noise ratios (SNRs) for confident assignment of (13)C-(13)C spin-coupled multiplet components within each (13)C resonance by (13)C NMR. The [U-(13)C]glucuronide isotopomer derived via direct pathway conversion of [U-(13)C]glucose to [U-(13)C]UDP-glucose was resolved from [1,2,3-(13)C(3)]- and [1,2-(13)C(2)]glucuronide isotopomers derived via Cori cycle or indirect pathway metabolism of [U-(13)C]glucose. In a second study, a group of four overnight-fasted patients (63 +/- 10 kg) with severe heart failure were given peppermint oil and infused with [U-(13)C]glucose for 4 hr (14 mg/kg prime, 0.12 mg/kg/min constant infusion) resulting in a steady-state plasma [U-(13)C]glucose enrichment of 4.6% +/- 0.6%. Menthol glucuronide was harvested and glucuronide (13)C-isotopomers were analyzed by (13)C NMR. [U-(13)C]glucuronide enrichment was 0.6% +/- 0.1%, and the sum of [1,2,3-(13)C(3)] and [1,2-(13)C(2)]glucuronide enrichments was 0.9% +/- 0.2%. From these data, flux of plasma glucose to hepatic UDPG was estimated to be 15% +/- 4% that of endogenous glucose production (EGP), and the Cori cycle accounted for at least 32% +/- 10% of GP.
Mendes
Ana C
AC
Department of Chemistry, University of Coimbra, Coimbra, Portugal.
Caldeira
M Madalena
MM
Silva
Claudia
C
Burgess
Shawn C
SC
Merritt
Matthew E
ME
Gomes
Filipe
F
Barosa
Cristina
C
Delgado
Teresa C
TC
Franco
Fatima
F
Monteiro
Pedro
P
Providencia
Luis
L
Jones
John G
JG
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D002247:Carbon Isotopes; D005260:Female; D005943:Gluconeogenesis / Q000502:physiology; D005947:Glucose / Q000378:metabolism*; D005965:Glucuronates / Q000652:urine*; D006801:Humans; D008099:Liver / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008610:Menthol / Q000031:analogs & derivatives* / Q000652:urine; D014532:Uridine Diphosphate Glucose / Q000737:chemistry*
D001786:Blood Glucose; D002247:Carbon Isotopes; D005965:Glucuronates; D008610:Menthol; C044963:menthol glucuronide; D005947:Glucose; D014532:Uridine Diphosphate Glucose