Effect of the level of dietary protein on the utilization of alpha-ketoisocaproate for protein synthesis

Journal Article · Tue Apr 01 04:00:00 EST 1986 · Am. J. Clin. Nutr.; (United States)

OSTI ID:5682486

Kang, C W; Tungsanga, K; Walser, M

The efficiency of alpha-ketoisocaproate (KIC) as a dietary substitute for leucine in rats on varying protein intake was estimated by an isotopic method, previously shown to yield the same results as comparative growth experiments. /sup 14/C-KIC and /sup 3/H-leucine are injected orally. Six hours later the ratio, R, of /sup 14/C//sup 3/H in isolated proteins, divided by the same ratio in the injectate is measured. This ratio has been shown to be approximately equal to nutritional efficiency of KIC relative to leucine. As dietary protein increased from 6.3% to 48.3%, whole body protein R decreased from 0.515 +/- 0.045 to 0.299 +/- 0.016. Variations with protein intake were noted in R of protein isolated from individual organs. The magnitude of R in these organs varied two-fold, in the following sequence: brain greater than heart greater than or equal to skeletal muscle greater than or equal to salivary gland greater than or equal to kidney greater than liver. Whole body protein R could be confidently predicted (r2 = 0.992) from R in the protein of kidney and muscle. Thus, the nutritional efficiency of KIC as a dietary substitute for leucine in individual organs as well as in the whole animal is strongly dependent on the level of protein intake.

• Research Organization: Johns Hopkins Univ., Baltimore, MD
• OSTI ID: 5682486
• Journal Information: Am. J. Clin. Nutr.; (United States), Journal Name: Am. J. Clin. Nutr.; (United States) Vol. 4; ISSN AJCNA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMALS
BODY
BRAIN
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CENTRAL NERVOUS SYSTEM
DIET
DIGESTIVE SYSTEM
DISTRIBUTION
ELEMENTS
GLANDS
HEART
INTAKE
ISOTOPE APPLICATIONS
ISOTOPE RATIO
KETO ACIDS
KIDNEYS
LABELLED COMPOUNDS
LEUCINE
LIVER
MAMMALS
MUSCLES
NERVOUS SYSTEM
NITROGEN
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RATS
RODENTS
TISSUE DISTRIBUTION
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES