Effect of denervation on the content of cardiac troponin-T and cardiac troponin-I in rat skeletal muscle

Abnormal rhabdomyocyte expression of cardiac troponin-T (cTnT) was thought to interfere with the cTnT assay. cTnT isoforms have been shown to be transiently expressed in skeletal muscle during development and in response to muscle denervation. The effect of denervation and aging on cTnT and cardiac troponin-I (cTnI) content in fast and slow rat skeletal muscles was assessed quantitatively. Sections of the tibial nerve were transected from one hind limb of both young (n=12) and old (n=12) rats. Animals were sacrificed at 1, 2, and 4 weeks after the operation, and the extensor digitorum longus (EDL) and the soleus were removed from both the denervated and the contralateral control limb. There was no significant difference in cTnI content between the fast EDL and slow soleus muscles. The cTnT content was significantly higher in the soleus than the EDL muscle (p<0.001). These data, combined with data on other models in the literature, indicate that re-expression of cTnT and cTnI isoforms in adult skeletal muscle is unlikely and does not interfere with cTnT assays for assessment of cardiac damage.