Abstract
This study set out to validate the use of 31P-NMR spectroscopy together with alanine ± glucagon infusions to assess hepatic gluconeogenic flux in vivo. Bolus infusions of alanine (2.8 or 5.6 mmol/kg) ± glucagon (250 μg/kg) were used. Maximal changes in the phosphomonoesters (PME), inorganic phosphate (P(i)) and β-NTP occurred 40 mins post infusion. ME increased 13.1% (p < 0.02) and 20.8% (P < 0.01) at 2.8 mmol/kg + glucagon and 5.6 mmol/kg ± glucagon, respectively. Pi was unaltered at 2.8 mmol/kg but increased by 28.8% (P < 0.01) at 5.6 mmol/kg alanine + glucagon. β-NTP decreased by 14.4% (P < 0.02) and 16.1% (P < 0.02) at 5.6 mmol/kg -/+ glucagon, respectively. This latter infusion showed slower recovery rates of NTP which remained 12.3% (P < 0.05) lower 70 min post infusion compared with pre-infusion values. 31P-NMR analysis of liver extracts revealed that PME increases were partly due to 3-phosphoglycerate and corroborated reductions in β-NTP and γ-NTP: β-NDP ratio upon infusion of 5.6 mmol/kg alanine ± glucagon. Hepatic glucose output from perfused liver experiments showed no difference between alanine concentrations indicating maximal glucose output at the lower concentration. This study has shown that in vivo 31P-NMR in combination with alanine infusion, can be used to determine metabolic changes associated with gluconeogenesis.
Original language | English |
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Pages (from-to) | 290-304 |
Number of pages | 15 |
Journal | Biochimica et Biophysica Acta - General Subjects |
Volume | 1335 |
Issue number | 3 |
DOIs | |
Publication status | Published - 6 Jun 1997 |
Externally published | Yes |
Keywords
- Alanine
- Gluconeogenesis
- In vitro
- In vivo
- Liver
- P-NMR