Effects of branched-chain amino acids on nitrogen metabolism in patients with cirrhosis

Authors

  • Fredrick L. Weber Jr. M.D,

    Corresponding author
    1. Department of Medicine, Division of Gastroenterology and Nutrition, Veterans Administration Medical Center, Cleveland, Ohio 44106
    2. University Hospitals, Case Western Reserve University Medical School, Cleveland, Ohio 44106
    • Department of Medicine, University Hospitals, 2074 Abington Road, Cleveland, OH 44106
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  • Brenda S. Bagby,

    1. Department of Medicine, Division of Gastroenterology and Nutrition, Veterans Administration Medical Center, Cleveland, Ohio 44106
    2. University Hospitals, Case Western Reserve University Medical School, Cleveland, Ohio 44106
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  • Lucilla Licate,

    1. Department of Medicine, Division of Gastroenterology and Nutrition, Veterans Administration Medical Center, Cleveland, Ohio 44106
    2. University Hospitals, Case Western Reserve University Medical School, Cleveland, Ohio 44106
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  • Steven G. Kelsen

    1. Department of Medicine, Division of Gastroenterology and Nutrition, Veterans Administration Medical Center, Cleveland, Ohio 44106
    2. University Hospitals, Case Western Reserve University Medical School, Cleveland, Ohio 44106
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Abstract

This study was conducted to determine whether an amino acid solution enriched with branched-chain amino acids altered protein catabolic rates and plasma ammonia in patients with cirrhosis. Nine stable subjects were given two peripheral intravenous infusions: a standard amino acid solution (solution A) and a branched-chain-enriched solution containing 97% more leucine (solution B). Each solution was given for separate 9-day (group 1, n = 6) or 3-day (group 2, n = 3) periods. Amino acid solutions delivered 0.7 gm protein kg−1 day−1. Diets provided an additional 0.3 gm protein plus maintenance calories. Protein turnover was assessed by a primed continuous infusion of [1-14C] leucine in six patients (three patients in group 1 and three patients in group 2). Nitrogen balance and urinary 3-methyl histidine excretion were determined in group 1 patients. Compared with solution A, solution B increased leucine flux and leucine oxidation but had no significant effect on protein synthesis or catabolism based on the plasma specific activity of either leucine or α-ketoisocaproic acid. The additional leucine infused with solution B was quantitatively oxidized. Nitrogen balance did not differ with the two solutions and there was also no difference in the urinary excretion of 3-methyl histidine, suggesting that muscle protein catabolism was unchanged. Plasma ammonia concentration decreased significantly during the infusion of solution B and was associated with a slight fall in plasma glucagon concentration. The results indicated that a branched-chain-enriched amino acid solution did not alter protein synthesis or catabolism although it did lower the plasma ammonia when compared with a standard amino acid formula in stable cirrhotic patients.(HEPATOLOGY 1990;11:942-950.).

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