CONTEXT: Skeletal muscle wasting has been associated with elevations in circulating inflammatory cytokines, in particular TNF-alpha. OBJECTIVE: In this study, we investigated whether TNF-alpha affects human systemic and skeletal muscleprotein turnover via a 4-h recombinant human (rh) TNF-alpha infusion. We hypothesize that TNF-alpha increases human muscle protein breakdown and/or inhibits synthesis. SUBJECTS AND METHODS: Using a randomized, controlled, crossover design, postabsorptive healthy young males (n = 8) were studied 2 h under basal conditions followed by a 4-h infusion of either rhTNF-alpha (700 ng . m(-2) . h(-1)) or 20% human albumin (control), which was the vehicle of rhTNF-alpha. Systemic and skeletal muscleprotein turnover was estimated by a combination of tracer dilution methodology (primed continuous infusion of l-[ring-(2)H(5)]phenylalanine and l-[(15)N-leucine], with prime of l-[ring-(2)H(4)]tyrosine) and femoral arterial-venous differences over the leg and muscle biopsies. RESULTS:Plasma TNF-alpha concentration rapidly increased from basal levels of approximately 0.7 to 17 pg . ml(-1) with rhTNF-alpha infusion. Whole body protein synthesis, breakdown, and net degradation were similar after the basal and infusion period of the control and rhTNF-alpha trials. Skeletal muscle, musculus vastus lateralis, protein fractional synthetic rate was not different over 4 h of control or rhTNF-alpha (rate of incorporation of (15)N-leucine). Muscle protein turnover determined with the phenylalanine three-compartment model showed similar muscle synthesis, breakdown, and net muscle degradation after 2-h basal and after 4-h control or rhTNF-alpha infusion. CONCLUSION: This study is the first to show in humans that TNF-alpha does not affect systemic and skeletal muscleprotein turnover, when acutely elevated for 4 h to moderate levels not causing adverse effects.
RCT Entities:
CONTEXT: Skeletal muscle wasting has been associated with elevations in circulating inflammatory cytokines, in particular TNF-alpha. OBJECTIVE: In this study, we investigated whether TNF-alpha affects human systemic and skeletal muscle protein turnover via a 4-h recombinant human (rh) TNF-alpha infusion. We hypothesize that TNF-alpha increases human muscle protein breakdown and/or inhibits synthesis. SUBJECTS AND METHODS: Using a randomized, controlled, crossover design, postabsorptive healthy young males (n = 8) were studied 2 h under basal conditions followed by a 4-h infusion of either rhTNF-alpha (700 ng . m(-2) . h(-1)) or 20% human albumin (control), which was the vehicle of rhTNF-alpha. Systemic and skeletal muscle protein turnover was estimated by a combination of tracer dilution methodology (primed continuous infusion of l-[ring-(2)H(5)]phenylalanine and l-[(15)N-leucine], with prime of l-[ring-(2)H(4)]tyrosine) and femoral arterial-venous differences over the leg and muscle biopsies. RESULTS: Plasma TNF-alpha concentration rapidly increased from basal levels of approximately 0.7 to 17 pg . ml(-1) with rhTNF-alpha infusion. Whole body protein synthesis, breakdown, and net degradation were similar after the basal and infusion period of the control and rhTNF-alpha trials. Skeletal muscle, musculus vastus lateralis, protein fractional synthetic rate was not different over 4 h of control or rhTNF-alpha (rate of incorporation of (15)N-leucine). Muscle protein turnover determined with the phenylalanine three-compartment model showed similar muscle synthesis, breakdown, and net muscle degradation after 2-h basal and after 4-h control or rhTNF-alpha infusion. CONCLUSION: This study is the first to show in humans that TNF-alpha does not affect systemic and skeletal muscle protein turnover, when acutely elevated for 4 h to moderate levels not causing adverse effects.
Authors: Douglas W Gould; Ian Lahart; Amtul R Carmichael; Yiannis Koutedakis; George S Metsios Journal: J Cachexia Sarcopenia Muscle Date: 2012-12-13 Impact factor: 12.910
Authors: Ermina Bach; Roni R Nielsen; Mikkel H Vendelbo; Andreas B Møller; Niels Jessen; Mads Buhl; Thomas K-Hafstrøm; Lars Holm; Steen B Pedersen; Henriette Pilegaard; Rasmus S Biensø; Jens O L Jørgensen; Niels Møller Journal: Diabetes Date: 2013-07-08 Impact factor: 9.461