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ACID‐BASE IN RENAL FAILURE: What Have Isotope Studies in Humans Told Us About the Nutritional Effects of Acidosis in Dialysis?
Author(s) -
Louden Jonathan D.,
Roberts Russell G.,
Goodship Timothy H. J.
Publication year - 2000
Publication title -
seminars in dialysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 78
eISSN - 1525-139X
pISSN - 0894-0959
DOI - 10.1046/j.1525-139x.2000.00067.x
Subject(s) - protein catabolism , medicine , acidosis , catabolism , amino acid , protein turnover , metabolic acidosis , lean body mass , protein degradation , in vivo , dialysis , endocrinology , protein metabolism , protein biosynthesis , biochemistry , metabolism , body weight , chemistry , biology , microbiology and biotechnology
In order to understand how acidosis might predispose to loss of lean body mass it is important to recognise that body protein is in a dynamic state with a daily turnover of approximately 300 g of protein in a 60 kg man. This is significantly greater than the daily protein intake at a level of 1 g · kg ‐1 · day ‐1 . Loss of lean body mass occurs when the balance between whole body protein synthesis and breakdown is negative. Measurement of whole body protein turnover is possible using either boluses or primed constant infusions of isotopically labelled amino acids. Previously, a variety of in vitro and in vivo animal studies have shown that acidosis increases protein degradation and amino acid oxidation. Several research groups including our own have used amino acid tracer techniques to examine whether protein degradation is increased in vivo in human subjects with acidosis and chronic renal failure. The results from these studies have shown a remarkable concordance with increased protein degradation in all groups of patients studied. However, the results for protein synthesis have been more difficult to interpret, with only a few studies directly measuring the effects of acidosis on amino acid incorporation into protein.