Of flux and flooding: the advantages and problems of different isotopic methods for quantifying protein turnover in vivo: I. Methods based on the dilution of a tracer.

摘要: The advantages and problems, both practical theoretical, of isotope dilution approaches to the determination whole-body tissue protein turnover are discussed. It was concluded that: (1) measurements made on basis labelling plasma breath well suited measurement body amino acid oxidation balance, but because problem inhomogeneity pools, this approach generally underestimates turnover; (2) in investigations nutritional effects turnover, closer attention should be paid first-pass splanchnic metabolism; (3) trans-organ tracer balance method, particularly if combined with labelling, is a potentially useful simultaneous dynamic synthesis degradation; (4) leucine may most label for level studies muscle synthesis, as recent have shown quite close isotopic equilibrium between muscle-free tRNA-bound pools.