Myosin-ATPase fibre typing of chemically skinned muscle fibres.

The efficacy of myosin (M)-ATPase fibre typing to differentiate fibre types in chemically (EGTA) skinned muscle fibres was investigated. Cryosections or single fibres from isolated bundles of chemically skinned rat extensor digitorum longus (EDL) and soleus (SOL) muscles were stained for M-ATPase activity. The results indicate that two major fibre types (type I and II, Brooke & Kaiser, 1970) can be identified, as well as subgrouping of the type II fibres into types IIa and IIb. Thus, chemically skinning muscle fibres appears to have no detrimental effects on subsequent M-ATPase fibre typing.