Plasma reciprocal pool specific activity predicts that of intracellular free leucine for protein synthesis

Journal Article · Fri Sep 01 04:00:00 EDT 1989 · American Journal of Physiology; (USA)

OSTI ID:5481853

Horber, F F; Horber-Feyder, C M; Krayer, S; Schwenk, W F; Haymond, M W ^[1]

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1. Mayo Clinic and Foundation, Rochester, MN (USA)

We previously proposed that, during the infusion of either labeled leucine or its alpha-ketoacid, alpha-ketoisocaproate (KIC), the plasma specific activity (SA) of the transaminated product of the infused tracer (reciprocal pool SA) may better reflect the intracellular leucine SA than the plasma SA of either infused tracer (primary pool SA). To test this hypothesis, 14 dogs were simultaneously infused intravenously with (3H)leucine and (14C)KIC, and blood and tissue compartments were sampled. The ratios of (3H)-leucine to (14C)leucine (3H)/(14C)leucine in mixed tissue proteins and in the intracellular space of striated muscle were the same as the ratio of the isotope infusion rates and similar, although slightly lower (P less than 0.01), than (3H)KIC/(14C)leucine SA (ratio of reciprocal pool SA) in plasma. Plasma (3H)KIC/(14C)leucine SA were essentially identical to the (3H)/(14C) of leucine in (1) mixed liver proteins, (2) intrahepatic free leucine, and (3) fibrin. The (3H)/(14C)leucine in mixed renal proteins and in the intracellular space of kidney and erythrocytes were similar to those of the venous plasma (3H)/(14C)leucine SA. The plasma (3H)KIC and (14C)leucine SA (the reciprocal pool SA) were similar to the SA of (3H)- and (14C)leucine in the intracellular space of all organs investigated with the exception of kidney. Therefore, in postabsorptive dogs, the plasma SA of the transaminated product of the infused labeled KIC or leucine is an excellent predictor of the intracellular leucine SA in all tissues investigated with the exception of kidney.

• OSTI ID: 5481853
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 257:3 Pt 1; ISSN 0002-9513; 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
BIOLOGICAL MATERIALS
BIOLOGICAL MODELS
BIOSYNTHESIS
BLOOD
BLOOD CELLS
BODY
BODY FLUIDS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
COAGULANTS
DOGS
DRUGS
ERYTHROCYTES
FIBRIN
HEMATOLOGIC AGENTS
HEMOSTATICS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
ISOTOPE RATIO
KIDNEYS
KINETICS
LABELLED COMPOUNDS
LEUCINE
MAMMALS
MATERIALS
MUSCLES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
REACTION KINETICS
SCLEROPROTEINS
SYNTHESIS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES