Abstract
The rate of plasma protein turnover is more rapid in dogs receiving adequate dietary protein than when a diet devoid of protein is fed. Both albumin and combined globulins are involved in this change. The difference in turnover is reflected in a total protein half-life of 4.8 days with protein feeding versus 7.8 days without protein in the diet and in the metabolism of 1.0 and 0.65 gm. per kilogram of body weight per day on the respective diets. Additions of dietary protein from 10 to 30 per cent caused no further increase in the rate of plasma protein turnover. With protein depletion due to plasmapheresis and a very low protein diet there is evidence of reduced protein metabolism as indicated by nitrogen retention as well as a reduction in total plasma protein breakdown and interchange of isotope between plasma and tissue proteins. Following introduction of labeled plasma protein into the circulation the net amount of isotope transferred to tissues has been computed from the difference between total plasma protein breakdown and combined C14 excretion in urine and expired air. In animals receiving adequate dietary protein, tissue transfer amounts to 70 per cent of the total lost from the plasma proteins each day while the percentage rises to 85 in depleted dogs deprived of protein. In dogs with both plasma and tissue proteins labeled it can be estimated that, under conditions of protein feeding, an amount of C14 approximately equal to that lost from the plasma must recycle to account for the observed decrease in Apparent plasma protein turnover rate, (t½ of 15 versus 5 days). Without protein in the diet the isotope contribution of the tissues to the maintenance of plasma protein levels must be as great as or greater than that transferred in the opposite direction.
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Selected References
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- BLAHD W. H., FIELDS M., GOLDMAN R. The turnover rate of serum albumin in the nephrotic syndrome as determined by I 131-labeled albumin. J Lab Clin Med. 1955 Nov;46(5):747–756. [PubMed] [Google Scholar]
- GOLDSWORTHY P. D., VOLWILER W. Mechanism of protein turnover studied with cystine-S35, lysine-C14 doubly labeled plasma proteins of the dog. J Biol Chem. 1958 Feb;230(2):817–831. [PubMed] [Google Scholar]
- JEFFAY H., WINZLER R. J. The metabolism of serum proteins. II. The effect of dietary protein on the turnover of rat serum protein. J Biol Chem. 1958 Mar;231(1):111–116. [PubMed] [Google Scholar]
- McFARLANE A. S. Use of labelled plasma proteins in the study of nutritional problems. Prog Biophys Biophys Chem. 1957;7:115–163. [PubMed] [Google Scholar]
- STEINBOCK H. L., TARVER H. Plasma protein. V. The effect of the protein content of the diet on turnover. J Biol Chem. 1954 Jul;209(1):127–132. [PubMed] [Google Scholar]
- STERLING K. The turnover rate of serum albumin in man as measured by I131-tagged albumin. J Clin Invest. 1951 Nov;30(11):1228–1237. doi: 10.1172/JCI102542. [DOI] [PMC free article] [PubMed] [Google Scholar]
- TERRY R., SANDROCK W. E. Parenteral plasma protein maintains nitrogen equilibrium over long periods. J Exp Med. 1948 Jun 1;87(6):547–559. doi: 10.1084/jem.87.6.547. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WASSERMAN K., MAYERSON H. S. Dynamics of lymph and plasma protein exchange. Cardiologia. 1952;21(4):296–307. doi: 10.1159/000165210. [DOI] [PubMed] [Google Scholar]
- YUILE C. L., LAMSON B. G., MILLER L. L., WHIPPLE G. H. Conversion of plasma protein to tissue protein without evidence of protein breakdown; results of giving plasma protein labeled with carbon 14 parenterally to dogs. J Exp Med. 1951 Jun;93(6):539–557. doi: 10.1084/jem.93.6.539. [DOI] [PMC free article] [PubMed] [Google Scholar]
- YUILE C. L., LUCAS F. V., JONES C. K., CHAPIN S. J., WHIPPLE G. H. Inflammation and protein metabolism studies of carbon-14-labeled proteins in dogs with sterile abscesses. J Exp Med. 1953 Aug;98(2):173–194. doi: 10.1084/jem.98.2.173. [DOI] [PMC free article] [PubMed] [Google Scholar]
- YUILE C. L., LUCAS F. V., NEUBECKER R. D., COCHRANE C. G., WHIPPLE G. H. Depletion of reserve protein from extravascular extracellular fluid; C14 labeling of plasma proteins in dogs after plasmapheresis. J Exp Med. 1959 Feb 1;109(2):165–171. doi: 10.1084/jem.109.2.165. [DOI] [PMC free article] [PubMed] [Google Scholar]
- YUILE C. L., O'DEA A. E., LUCAS F. V., WHIPPLE G. H. Plasma protein labeled with lysine-epsilon-C14; its oral feeding and related protein metabolism in the dog. J Exp Med. 1952 Sep;96(3):247–254. doi: 10.1084/jem.96.3.247. [DOI] [PMC free article] [PubMed] [Google Scholar]