• Gianni Biolo, Marcello De Cicco, Viviana Dal Mas, Stefania Lorenzon, Raffaella Antonione, Beniamino Ciocchi, Rocco Barazzoni, Michela Zanetti, Franca Dore, and Gianfranco Guarnieri.
• Department of Clinical, Technological and Morphological Sciences, Division of Internal Medicine, University of Trieste, Trieste, Italy. biolo@units.it
• Nutrition. 2006 May 1;22(5):475-82.

ObjectivePatients with cancer are characterized by decreased muscle protein synthesis and glutamine availability that contribute to an impaired immune response. These abnormalities worsen after surgical stress. We tested the hypothesis that pharmacologic doses of branched-chain amino acids would improve the early metabolic response after major cancer surgery.MethodsBy using a crossover experimental design, we compared the metabolic effects of isonitrogenous solutions of balanced and branched-chain-enriched amino acid mixtures infused at the rate of 82 mg x h(-1) x kg(-1) for 3 h in patients with colorectal or cervical cancer on the first and second days after radical surgery combined with intraoperative radiation therapy. The ratios of leucine to total amino acid (grams) in the two mixtures were 0.09 and 0.22, respectively. Muscle protein and glutamine kinetics were determined by using stable isotope of amino acids and the leg arteriovenous balance technique. Glucose and insulin were continuously infused throughout the 2-d study to maintain near euglycemia.ResultsRates of muscle protein synthesis and degradation were not significantly affected by the balanced amino acid infusion. In contrast, the isonitrogenous, branched-chain-enriched amino acid mixture accelerated muscle protein turnover by stimulating (P ConclusionsAn excess of branched-chain amino acids in the presence of an optimal profile of other essential amino acids acutely increased muscle protein synthesis and glutamine flux from skeletal muscle in cancer patients after surgery.

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