The effect of chronic tumour necrosis factor-alpha treatment on urinary nitrogen excretion in the rat.

Chronic tumour necrosis factor-alpha (TNF) treatment of rats for 4 days resulted in transient decreases in food intake and body weight, 24 h after the beginning of the cytokine treatment. Treatment with the cytokine resulted in a large increase in circulating urea concentrations. The urinary excretion of urea and creatinine is increased following TNF treatment. 3-methylhistidine, an indicator of contractile protein breakdown, is also elevated in the urine of the animals treated with the cytokine. From previous observations (1) and the data presented here, it is suggested that TNF enhanced muscle catabolism even in experimental situations were body weight loss was not apparent.