CORRELATION OF MATPASE, PARVALBUMIN, AND CYTOCHROME-C-OXIDASE IN RAT SKELETAL-MUSCLE FIBERS

Muscle fibre typing is conventionally performed on unfixed frozen sect ions. Within the particular classes of fibre types mATPase correlates well with the type of myosin heavy chain (MHC). However, investigation of other properties, e.g., parvalbumin (PV) level, cannot be determin ed on unfixed frozen sections. Determination of PV, which correlates w ith the relaxation time, is performed immunohistochemically on fixed t issue. By that method a comparison of mATPase activity and the amount of PV within the same muscle fibre is difficult. The present method, c ombining histochemistry of mATPase and cytochrome c oxidase with parva lbumin immunohistochemistry on consecutive sections, allows the distin ction of six fibre types: I, IB, IIA, IIB, IIAB, IIX, and a C fibre po pulation without division into IC and IIC fibres. The advantages and d isadvantages of the present method are discussed.