Acute treatment with tumour necrosis factor-alpha induces changes in protein metabolism in rat skeletal muscle.
Acute treatment of rats with recombinant tumour necrosis factor (TNF-alpha) caused an enhanced proteolytic rate--measured as tyrosine released in the presence of cycloheximide-in soleus 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 in extensor digitorum longus (EDL) (26%) muscle. In addition, treatment of rats with TNF-alpha increased amino acid uptake by transport system A in the incubated muscles both in soleus (45%) and EDL (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 alpha(methyl)-aminoisobutyric acid by the incubated muscles. It can be concluded that acute TNF-alpha treatment causes changes in protein metabolism in red-type muscles-such soleus-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.
García-Martínez
C
C
Department de Bioquímica i Fisiologia, Facultat de Biologia, Universitat de Barcelona, Spain.
López-Soriano
F J
FJ
Argilés
J M
JM
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D009124:Muscle Proteins / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D014443:Tyrosine / Q000378:metabolism
D000596:Amino Acids; D009124:Muscle Proteins; D014409:Tumor Necrosis Factor-alpha; D014443:Tyrosine; D003513:Cycloheximide