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Endogenous loss of leucine and methionine in adult male rats

Published online by Cambridge University Press:  06 August 2007

R. J. Neale  and
J. C. Waterlow
R. J. Neale
Affiliation:
Department of Applied Biochemistry and Nutrition, University of Nottingham, School of Agriculture, Sutton Bonington, Loughborough, LE12 5RD
J. C. Waterlow
Affiliation:
Department of Human Nutrition, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT
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Abstract

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1. The fractional rate of loss of 14C and body-weight was measured in adult male rats after giving 14C-labelled methionine or leucine and maintaining rats for 30 d on a low-protein or a specific methionine+cystine-free diet: carcasses were then analysed for protein and fat 14C radioactivity.

2. The fractional loss of 14CO2 from [14C]methionine or [14C]leucine between day 20 and day 30 was always greater than the fractional loss of body-weight.

3. Carcass protein 14C radioactivity after giving [14C]leucine was higher than after giving [14C]methionine, but fat 14C radioactivity after either 14C-labelled amino acid was only a small proportion of the total body 14C radioactivity.

4. After correction of the fractional loss of 14CO2 for urinary 14C loss, but not body-weight loss, absolute amino acid loss was calculated using published values for methionine and leucine content of rats.

5. The best estimates of endogenous amino acid loss obtained using 1-14C-labelled amino acids, expressed as mg/kg body-weight0.75 per day were leucine 79, methionine 38.

Type
Papers of direct relevance to Clinical and Human Nutrition
Information
British Journal of Nutrition , Volume 37 , Issue 2 , March 1977 , pp. 259 - 268
Copyright
Copyright © The Nutrition Society 1977

References

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