As an initial step for investigating the morphological and biochemical changes accompanying muscle hypertrophy in inbred mouse strains, the proteins of hypertrophied muscles were compared with those of control muscles. Compensatory hypertrophy was induced by tenotomy of mouse skeletal muscles and the muscle proteins were analyzed electrophoretically. NZW/N and A/J mice about 7 weeks old strain were used. The tenotomy method, developed by Denny- Brown, was used for applying a work load to skeletal muscles. Muscle showing compensatory hypertrophy at 7 days after operation were kept for analysis at -90°C.
　The frozen muscle was then homogenized in liquid nitrogen and resolved in SDS-buffer for the Laemmli electrophoresis system. The extract was boiled for 5 min at 100°C in a water bath. Sodium dodecylsulfate polyacrylamide electrophoresis of muscle proteins was carried out as described by Laemmli using 10% acrylamide gel in a slab gel electrophoresis apparatus. Comparison of the electrophoretic patterns of soleus muscle protein between NZW/N and A/J mice showed a conspicuous difference in both staining intensity and protein pattern. Similar results were also observed for the plantaris muscle. An especially conspicuous difference of staining intensity was seen for a protein corresponding to a molecular mass 68 KDa between control and hypertrophic plantaris muscle. This increment of 68 KDa protein after tenotomy was observed in both NZW/N and A/J mice. Therefore, the increase and decrease of this 68 KDa protein might be closely related to work-induced skeletal muscle hypertrophy.

DESCENTE SPORTS SCIENCE Vol.13/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE