/sup 13/C and /sup 31/P NMR study of gluconeogenesis: utilization of /sup 13/C-labeled substrates by perfused liver from streptozotocin-diabetic and untreated rats
The metabolism of /sup 13/C-labeled substrates was followed by /sup 13/C and /sup 31/P NMR in perfused liver from the streptozotocin-treated rat model of insulin-dependent diabetes. Comparison was made with perfused liver from untreated littermates, fasted either 24 or 12 h. The major routes of pyruvate metabolism were followed by a /sup 13/C NMR approach that provided for the determination of the metabolic fate of several substances simultaneously. The rate of gluconeogenesis was 2-4-fold greater and ..beta..-hydroxybutyrate production was 50% greater in liver from the chronically diabetic rats as compared with the control groups. Large differences in the distribution of /sup 13/C label in hepatic alanine were measured between diabetic and control groups. The biosyntheses of /sup 13/C-labeled glutathione and N-carbamoylaspartate were monitored in time-resolved /sup 13/C NMR spectra of perfused liver. Assignments for the resonances of glutathione and N-carbamoylaspartate were made with the aid of /sup 13/C NMR studies of perchloric acid extracts of the freeze-clamped livers. /sup 13/C NMR spectroscopy of the perfusates provided a convenient, rapid assay of the rate of oxidation of (2-/sup 13/C)ethanol, the hepatic output of (2-/sup 13/)acetaldehyde, and the accumulation of (2-/sup 13/C)acetate in the perfusate. By /sup 31/P NMR spectroscopy, carbamoyl phosphate was measured in all diabetic livers and an unusual P,P'-diesterified pyrophosphate was observed in one-fourth of the diabetic livers examined. Neither of these phosphorylated metabolites was detected in control liver. Both /sup 13/C and /sup 31/P NMR were useful in defining changes in hepatic metabolism in experimental diabetes.
- Research Organization:
- Merck Sharp and Dohme Research Labs., Rahway, NJ
- OSTI ID:
- 6521634
- Journal Information:
- Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:2; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
ACETALDEHYDE
ALCOHOLS
ALDEHYDES
ANIMAL TISSUES
ANIMALS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
ANTINEOPLASTIC DRUGS
BIOLOGICAL PATHWAYS
BODY
CARBON 13
CARBON ISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DIABETES MELLITUS
DIGESTIVE SYSTEM
DISEASES
DRUGS
ENDOCRINE DISEASES
ETHANOL
EVEN-ODD NUCLEI
FASTING
GLANDS
HYDROXY COMPOUNDS
ISOTOPES
KETO ACIDS
LABELLED COMPOUNDS
LIGHT NUCLEI
LIVER
MAGNETIC RESONANCE
MAMMALS
METABOLIC DISEASES
METABOLISM
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
OXIDATION
PERFUSED TISSUES
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
PYRUVIC ACID
RATS
RESONANCE
RODENTS
STABLE ISOTOPES
STREPTOZOCIN
SUBSTRATES
TISSUES
VERTEBRATES