Investigation of apparent isotope effect between /sup 13/CO/sub 2/ and /sup 14/CO/sub 2/ trioctanoin breath tests. [Rats, comparison of oxidation of /sup 13/C and /sup 14/C acetate, octanoate, and trioctanoin]
A decrease in the recovery of /sup 13/CO/sub 2/ relative to /sup 14/CO/sub 2/ has been previously reported at low oxidation rates of 1-C- labeled trioctanoin. To determine whether or not this phenomenon is due to an isotope effect, and if so, to identify the metabolic step at which it occurs, the in vivo oxidation of /sup 13/C and /sup 14/C acetate, octanoate and trioctanoin were compared. The /sup 13/C and /sup 14/C substrates were administered simultaneously to rats whose expired CO/sub 2/ was collected in 1N NaOH, and subsequently released by acidification, and cryogenically purified in vacuum. Total CO/sub 2/ was measured manometrically, and the /sup 14/C and /sup 13/C recoveries were determined by scintillation counting and mass spectrometry, respectively. The trioctanoin breath tests did not reproduce the previously reported isotopic discrepancy. Further investigation revealed that the emulsified corn oil used as a pancreatic stimulant significantly depressed the endogenous /sup 13/CO/sub 2/ abundance in breath and caused the discrepancy. These studies did reveal a small time delay in the appearance of /sup 14/CO/sub 2/ relative to /sup 13/CO/sub 2/ during the trioctanoin breath test, which is probably due to a kinetic isotope effect. This difference in oxidation rates, however, is too small to affect the results of clinical breath tests.
- Research Organization:
- Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 6477911
- Report Number(s):
- CONF-780501-8
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BREATH
CARBON 13
CARBON 14
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON ISOTOPES
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
CLEARANCE
COUNTING TECHNIQUES
DIAGNOSTIC TECHNIQUES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXCRETION
EXHALATION
INHALATION
INTAKE
ISOTOPES
LIGHT NUCLEI
MAMMALS
MASS SPECTROMETERS
MEASURING INSTRUMENTS
METABOLISM
MONOCARBOXYLIC ACIDS
NUCLEI
OCTANOIC ACID
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
RADIOISOTOPE SCANNING
RADIOISOTOPES
RATS
RODENTS
SCINTISCANNING
SPECTROMETERS
STABLE ISOTOPES
TESTING
VERTEBRATES
YEARS LIVING RADIOISOTOPES