Summary
Not many studies have been done on protein turnover during recovery from malnutrition. Some relevant information can, however, be obtained from measurements on normal growing animals, since rehabilitation and normal growth have in common a rapid rate of net protein synthesis. The key question is the extent to which net gain in protein results from an increase in synthesis or a decrease in breakdown or both.
Different studies have used different methods, and all methods for measuring protein turnover have some disadvantages and sources of error. It is important to bear this in mind in evaluating the results. Consequently, part of this paper will be devoted to questions of methodology.
Whole body protein turnover has been measured in children recovering from severe malnutrition. During the phase of rapid catch-up growth the rate of protein synthesis is increased. As might be expected, it increases linearly with the rate of weight gain. At the same time there is a smaller increase in the rate of protein breakdown. The resultant of these two processes is that, over and above the basal rate of protein synthesis, 1.4 grams of protein have to be synthesized for 1 gram to be laid down. Very similar results have been obtained in rapidly growing young pigs.
Experimental studies on muscle growth in general confirm the conclusion that, at least in muscle, rapid growth is associated with rapid rates of protein breakdown as well as of synthesis. This has been shown in muscles of young growing rats, as well as in muscles in which hypertrophy has been induced by stretch or other stimuli. In contrast, the evidence suggests that rapid growth involves a fall in the rate of protein degradation.
The magnitude of the nitrogen balance under any conditions is determined by the difference between synthesis and breakdown. In the absence of any storage of amino acids, this must be the same as the difference between intake and excretion (S — B = I — E). A question of great interest is whether, at a given intake, the extent of N balance is determined primarily by regulation of synthesis and breakdown or by regulation of amino acid oxidation. Clearly, a reduction in amino acid degradation is equivalent to an increase in amino acid intake. An interesting subject for future research is the extent to which the amino acid degrading enzymes adapt to the requirements imposed by growth and rehabilitation.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Bates, P.C. & Millward, D.J. (1981) Characteristics of skeletal muscle growth and protein turnover in a fast-growing rat strain. Br. J. Nutr. 46: 7–13.
Brooke, O.G. & Ashworth, A. (1972) The influence of malnutrition on the postprandial metabolic rate and respiratory quotient. Br. J. Nutr. 27: 407–415.
Clugston, G.A. & Garlick, P.J. (1982a) The response of protein and energy metabolism to food intake in lean and obese man. Hum. Nutr. Clin. Nutr. 36C: 57–70.
Clugston, G.A. & Garlick, P.J. (1982b) The response of whole-body protein turnover to feeding in obese subjects given a protein-free diet for three weeks. Hum. Nutr. Clin. Nutr. 36C: 391–397.
Fern, E.B. & Garlick, P.J. (1974) The specific radioactivity of the tissue free amino acid pool as a basis for measuring the rate of protein synthesis in the rat in vivo. Biochem. J. 142: 413–419.
Fern, E.B., Garlick, P.J., McNurlan, M.A. & Waterlow, J.C. (1981) The excretion of isotope in urea and ammonia for estimating protein turnover in man with 15N glycine. Clin. Sci. 61: 217–228.
Garlick, P.J., Clugston, G.A. & Waterlow, J.C. (1980a) Influence of low energy diets on whole-body protein turnover in obese subjects. Am. J. Physiol. 238: E235-E244.
Garlick, P.J., McNurlan, M.A. & Preedy, V.R. (1980b) A rapid and convenient technique for measuring the rate of protein synthesis in tissues by injection of 3H phenylalanine. Biochem. J. 192: 719–723.
Golden, M.H.N. & Waterlow, J.C. (1977) Total protein synthesis in elderly people: A comparison of results with 15N/glycine and 14C/leucine. Clin. Sci. & Mol. Med. 53: 277–288.
Golden, M.H.N., Waterlow, J.C. & Picou, D. (1977a) Protein turnover, synthesis and breakdown before and after recovery from protein-energy malnutrition. Clin. Sci. & Mol. Med. 53: 473–477.
Golden, M.H.N., Waterlow, J.C. & Picou, D. (1977b) The relationship between dietary intake, weight change, nitrogen balance, and protein turnover in man. Am. J. Clin. Nutr. 30: 1345–1348.
Jackson, A.A. & Golden, M.H.N. (1981) Interrelationships of amino acid pools and protein turnover. In: Nutrition Metabolism in Man (Ed. Waterlow, J.C. & Stephen, J.M.L.) Applied Science Publishers, London & New Jersey, pp. 361–373.
Laurent, G.J., Sparrow, M.A. & Millward, D.J. (1978) Turnover of muscle protein in the fowl — Changes in the rate of protein synthesis and breakdown during hypertrophy of the anterior and posterior latissimus dorsi muscles. Biochem. J. 176: 407–417.
Matthews, D.E., Motil, K.J., Rohrbaugh, D.K., Burke, J.F., Young, V.R. & Bier, D.M. (1980) Measurements of leucine metabolism in man from a primed continuous infusion of L — 1 – 13C leucine. Am. J. Physiol. 238: E473-E479.
Mendes, C.B. & Waterlow, J.C. (1958) The effect of a low-protein diet and of refeeding on the composition of the liver and muscle in the weanling rat. Br. J. Nutr. 12: 74–88.
Motil, K.J., Matthews, D.E., Bier, D.M., Burke, J.F., Munro, H.N. & Young, V.R. (1981) Whole-body leucine and lysine metabolism: Response to dietary protein intake in young men. Am. J. Physiol. 240: E712-E721.
Picou, D. & Taylor-Roberts, T. (1969) The measurement of total protein synthesis and catabolism and nitrogen turnover in infants in different nutritional states receiving different amounts of dietary protein. Clin. Sci. 36: 283–296.
Reeds, P.J., Cadenhead, A., Fuller, M.F., Lobley, G.E. & McDonald, J.D. (1980) Protein turnover in growing pigs. Effects of age and food intake. Br. J. Nutr. 43: 445–455.
Sprinson, D.B. & Rittenberg, D. (1949) The rate of interaction of the amino acids of the diet with the tissue proteins. J. Biol. Chem. 180: 715–716.
Steffee, W.P., Goldmith, R.S., Pencharz, P.B., Scrimshaw, N.S. & Young, V.R. (1976) Dietary protein intake and dynamic aspects of whole-body protein turnover in obese subjects. Metabolism 25: 281–297.
Waterlow, J.C. & Jackson, A.A. (1981) Nutrition and protein turnover in man. Br. Med. Bull. 37: 5–10.
Waterlow, J.C., Garlick, P.J. & Millward, D.J. (1978a) Protein Turnover in Mammalian Tissues and in the Whole Body. Elsevier/North Holland, Amsterdam.
Waterlow, J.C., Golden, M.H.N. & Garlick, P.J. (1978b) Protein turnover in man measured with 15N: Comparison of end products and dose regimes. Am. J. Physiol. 235: E165-E174.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1983 Springer Basel AG
About this chapter
Cite this chapter
Fern, E.B., Waterlow, J.C. (1983). Protein Turnover, Nitrogen Balance and Rehabilitation. In: Mauron, J. (eds) Nutritional Adequacy, Nutrient Availability and Needs. Experientia Supplementum, vol 44. Birkhäuser, Basel. https://doi.org/10.1007/978-3-0348-6540-1_7
Download citation
DOI: https://doi.org/10.1007/978-3-0348-6540-1_7
Publisher Name: Birkhäuser, Basel
Print ISBN: 978-3-0348-6542-5
Online ISBN: 978-3-0348-6540-1
eBook Packages: Springer Book Archive