PROTEIN-METABOLISM IN RHEUMATOID-ARTHRITIS AND AGING - EFFECTS OF MUSCLE STRENGTH TRAINING AND TUMOR-NECROSIS-FACTOR-ALPHA

Objective. To determine the effects of rheumatoid arthritis (RA) on wh ole-body protein metabolism. Methods. We examined protein metabolism a nd its hormonal and cytokine mediators before and 12 weeks after progr essive resistance muscle strength training in 8 healthy young (mean +/ - SD age 25 +/- 2 years) and 8 healthy elderly (70 +/- 5 years) men an d women, and in 8 adults with RA (42 +/- 13 years). An additional 6 he althy elderly subjects (69 +/- 3 years) served as a swimming-only cont rol group. Results. Subjects with RA had higher rates of protein break down than did young or elderly healthy subjects (79.9 +/- 17.2 versus 60.3 +/- 5.8 and 63.7 +/- 12.4 mu moles/gm total body potassium/hour, respectively, P < 0.05), while there was no effect of age per se. Pati ents treated with methotrexate had normal rates of protein breakdown ( P < 0.01 versus RA without methotrexate; P not significant versus heal thy young subjects). Increased protein catabolism in RA was no longer evident after strength training, In multiple regression analysis, leve ls of tumor necrosis factor alpha (TNF alpha) (r = 0.47, P = 0.01) and growth hormone (r = -0.51, P = 0.006) were associated with protein br eakdown, and plasma glucagon levels were inversely correlated with pro tein synthesis (r = -0.45, P = 0.02), Growth hormone (r = -0.56, P = 0 .002) and glucagon (r = 0.45, P = 0.04, levels were associated with pr otein oxidation. Conclusion. Adults with RA have increased whole-body protein breakdown, which correlates with growth hormone, glucagon, and TNF alpha production.