Fibre type specificity of haem oxygenase-1 induction in rat skeletal muscle.

The expression of the inducible haem oxygenase (HO-1) gene was examined in different skeletal muscles. Rats were treated with haemin and a time course of HO-1 mRNA expression was determined in soleus and extensor digitorum longus (EDL) muscles. Fibre type composition and tissue myoglobin content were also measured. We found that HO-1 mRNA expression markedly increased in soleus (type I fibres) muscle but was only slightly affected in EDL (type II fibres). HO-1 expression directly correlated with both percentage of red fibres and tissue myoglobin. These data demonstrate that HO-1 gene expression follows a fibre type-specific pattern which might indicate an important role for this protein in the maintenance of skeletal muscle function.