Estimation of whole body protein synthesis from oxidation of infused (1- sup 14 C)leucine

Journal Article · Mon Jan 01 04:00:00 EST 1990 · American Journal of Physiology; (USA)

OSTI ID:6994553

Yagi, M; Walser, M ^[1]

---

1. Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA)

In rats infused with NaH{sup 14}CO{sub 3}, {sup 14}CO{sub 2} exhalation approached an asymptotic rate equal to 96.0 +/- 1.3 (SD) % of the infusion rate of {sup 14}C in a monoexponential manner with a half-time of 20 min. In rats infused with (1-{sup 14}C)leucine, {sup 14}CO{sub 2} exhalation (/0.96) approached an asymptotic value, (1-F), of 16-25% of {sup 14}C infusion rate (mean 20.4%) in a monoexponential manner with a half-time of approximately 31 min. Whole body protein synthesis (S) was calculated from 1-F and urea N plus ammonia N excretion (C) as S = CF/(1-F). S was a uniform function of body weight in these rats, in six additional rats in which S was measured 6 h after single intravenous injection of (1-{sup 14}C)leucine and also in previously reported rats given single injections. The relationship was S (mg.100 g-1.h-1) = 11-0.143 body wt (g) +/- 8.3. In six of these rats, S was also estimated from the plateau specific activity of plasma leucine or plasma 2-ketoisocaproate (KIC); the former estimate of S was significantly lower (by an average of 17%), but S was the same when specific activity of KIC was employed. These results support the validity of the expired {sup 14}CO{sub 2} technique for measuring S.

• OSTI ID: 6994553
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 258; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METALS
AMIDES
AMINO ACIDS
ANIMALS
BIOSYNTHESIS
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACIDS
CHALCOGENIDES
ELEMENTS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEUCINE
MAMMALS
METABOLISM
METALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PROTEINS
RATS
RESPIRATION
RODENTS
SODIUM
SYNTHESIS
TRACER TECHNIQUES
UREA
VERTEBRATES