Changes of myosin and its ATPase in experimentally induced fiber transformation in the rat

It has been reported that a reversible muscle fiber transformation was effected within a short time in the sternohyoid muscle of the rat by the removal of the contralateral muscle. In the present investigation the muscles were analyzed histochemically and biochemically. The fiber transformation was easily detected histochemically by the appearance of slow type I fibers, as this fiber type is almost lacking in control muscles. In two-dimensional electrophoresis the light chain pattern of the experimental and control muscles was similar. However, the peptide pattern of the heavy chains revealed clear differences between control and experimental muscles. The muscle fiber transformation found was reflected in the myosin heavy chain which is the site of ATPase activity. For transformation of the light chain pattern probably a much stronger stimulus is needed.