Trioctanoin infusion increases in vivo leucine oxidation: a lesson in isotope modeling

Journal Article · Mon Sep 01 04:00:00 EDT 1986 · Am. J. Physiol.; (United States)

OSTI ID:5073419

Rodriguez, N; Schwenk, W F; Beaufrere, B; Miles, J M; Haymond, M W

We have reported that infusion of trioctanoin in conscious dogs had little effect on leucine oxidation but decreased the rate of appearance (Ra) and interconversion of leucine and its alpha-keto acid, alpha-ketoisocaproate (KIC). To verify that these conclusions were independent of the leucine tracers and isotope models employed, the studies were repeated using (1-/sup 14/C)leucine and (4,5-/sup 3/H)KIC rather than (1-/sup 14/C)KIC and (4,5-/sup 3/H)leucine. In the present study, leucine oxidation calculated using the plasma (/sup 14/C)leucine or (/sup 14/C)KIC specific activities (SA) increased nearly twofold (P less than 0.001) during trioctanoin infusion in direct contrast to our previous results. When the data from either study were analyzed using the plasma SA of the leucine moiety reciprocal to the infused tracer as a potential indicator of the intracellular leucine SA, similar conclusions were obtained from either study: trioctanoin infusion in conscious dogs appears to increase whole-body leucine oxidation and does not decrease proteolysis. These studies challenge the validity of previously used isotope models of leucine metabolism and suggest that the plasma KIC SA during infusion of labeled leucine may most accurately reflect changes in whole-body leucine metabolism.

• Research Organization: Mayo Clinic and Foundation, Rochester, MN
• OSTI ID: 5073419
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States); ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMALS
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DOGS
ESTERS
ISOTOPE APPLICATIONS
KETO ACIDS
KINETICS
LABELLED COMPOUNDS
LEUCINE
LIPIDS
MAMMALS
METABOLISM
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDATION
REACTION KINETICS
TRACER TECHNIQUES
TRIGLYCERIDES
TRITIUM COMPOUNDS
VERTEBRATES