Apparent decreased oxidation and turnover of leucine during infusion of medium-chain triglycerides

Journal Article · Thu Aug 01 04:00:00 EDT 1985 · Am. J. Physiol.; (United States)

OSTI ID:5022789

Beaufrere, B; Tessari, P; Cattalini, M; Miles, J; Haymond, M W

A potential effector of the protein-sparing adaptation to fasting could be the increased availability of endogenous long-chain fatty acids. Were this hypothesis correct, infusion of medium-chain triglycerides to increase the plasma concentration of medium-chain fatty acids might also result in protein sparing. However, in most in vitro studies in rat muscle, octanoate increases the oxidation of the essential amino acid leucine. Therefore, leucine metabolism was assessed with infusions of (/sup 3/H)leucine and a-(/sup 14/C)ketoisocaproate ((/sup 14/C)KIC) before and during an infusion of trioctanoin in conscious dogs. Plasma octanoate increased from less than 30 to 528 microM over the 3 h of infusion. Plasma leucine and KIC concentrations decreased by 65-70% (P less than 0.01) over the first 2 h of infusion. Leucine oxidation, estimated from the expired /sup 14/CO/sub 2/ and the plasma (/sup 14/C)KIC specific activity, as well as from an open two-pool model, decreased. By use of these isotope models, the rates of leucine coming from and going to protein decreased (P less than 0.05 to P less than 0.01). Interconversion of leucine and KIC estimated from the open two-pool model decreased by 80% (P less than 0.01). These changes were accompanied by a 36% decrease in the plasma concentration of total plasma amino acids. Within the confines of the isotope models employed, these data are consistent with the hypothesis that increased fatty acid oxidation decreases protein turnover and may spare essential amino acids.

• Research Organization: Mayo Clinic, Rochester, MN
• OSTI ID: 5022789
• 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

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMALS
BIOLOGICAL MODELS
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
DOGS
ESTERS
HORMONES
INSULIN
ISOTOPE APPLICATIONS
KETO ACIDS
LABELLED COMPOUNDS
LEUCINE
LIPIDS
MAMMALS
METABOLISM
MUSCLES
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PEPTIDE HORMONES
PROTEINS
RATS
REDOX REACTIONS
RODENTS
TRACER TECHNIQUES
TRIGLYCERIDES
TRITIUM COMPOUNDS
VERTEBRATES