, Volume 125, Issue 1, pp 11-18

Acute treatment with tumour necrosis factor-α induces changes in protein metabolism in rat skeletal muscle

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Abstract

Acute treatment of rats with recombinant tumour necrosis factor (TNF-α) caused an enhanced proteolytic rate —measured as tyrosine released in the presence of cycloheximide — insoleus muscle (34%). The cytokine treatment also decreased the rate of protein synthesis in this muscle (22%) while it had no effect upon the same parameter inextensor digitorum longus (EDL) (26%) muscle. In addition, treatment of rats with TNF-α increased amino acid uptake by transport system A in the incubated muscles both insoleus (45%) andEDL (99%) in the presence of insulin in the incubating medium. This effect was not associated with a direct action of TNF on muscle since the addition of different concentrations of the cytokine to the preparations did not alter the uptake of α-(methyl)-aminoisobutyric acid by the incubated muscles. It can be concluded that acute TNF-α treatment causes changes in protein metabolism in red-type muscles — suchsoleus — while little effects are seen in white-type muscles — such as EDL. The results presented may, to some extent, be related to the cachectic response associated with cancer and inflammation.