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This Article Full Text Full Text (PDF) All Versions of this Article: 289/6/E1064    most recent 00141.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Katsanos, C. S. Articles by Wolfe, R. R. Search for Related Content PubMed PubMed Citation Articles by Katsanos, C. S. Articles by Wolfe, R. R.

Method for the determination of the arteriovenous muscle protein balance during non-steady-state blood and muscle amino acid concentrations

¹Departments of Surgery, Shriners Hospitals for Children-Galveston and Departments of ²Internal Medicine and ³Anesthesiology, University of Texas Medical Branch, Galveston, Texas; and ⁴AminoScience Laboratories, Ajinomoto Company, Incorporated, Kawasaki, Japan

Submitted 29 March 2005 ; accepted in final form 13 July 2005

We describe a method based on the traditional arteriovenous balance technique in conjunction with muscle biopsies for the determination of leg muscle protein balance during the nonsteady state in blood amino acid concentrations. Six young, healthy individuals were studied in the postabsorptive state (pre-Phe) and after a bolus ingestion of 0.5 g phenylalanine (post-Phe). Post-Phe free phenylalanine concentrations in blood and muscle increased (P < 0.05), but the respective concentrations of the amino acid threonine did not change. The average post-Phe leg net balance (NB) for threonine decreased from basal (P < 0.05), but that for phenylalanine did not change. A volume of distribution for free phenylalanine in the leg was calculated based on the leg lean mass and the relative muscle water content and used to estimate the rate of accumulation of free phenylalanine in the leg. When the post-Phe NB for phenylalanine was corrected for the rate of accumulation of free phenylalanine in the leg, the post-Phe NB for phenylalanine decreased from basal (P < 0.05). This corrected value was not different (P > 0.05) from the value predicted for the phenylalanine NB based on the pre- and post-Phe NB responses for threonine. We conclude that the protein NB in non-steady-state blood phenylalanine concentrations can be determined from the arteriovenous phenylalanine NB by accounting for changes in free phenylalanine within its volume of distribution.

methodology; phenylalanine net balance; intracellular phenylalanine; volume of distribution

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