The effect of salt loading on compensatory muscle hypertrophy and muscle atrophy induced by tenotomy was studied to ascertain the effect of salt loading on the muscle metabolism in Wister rats. The increment of body weights in the 1.8% salt loading group is less than the control group. It was suggested that the change of body weights in the 1.8% salt loading group was mainly caused by low intake of foods. The examination was started on the 10th day when body weight was influenced by salt loading. Compensatory hypertrophy of soleus was noted in all groups. However, compensatory hypertrophy of the plantaris muscle which is fast muscle was not induced by tenotomy in the 1.8% salt loading group. Blood urea nitrogen which was an index of the protein degradation in the whole body was the lower values in the salt loading groups than the control group. The sodium concentration in serum was not reflected by volume of salt loading. On the contrary, the sodium concentration in serum in 0.9% salt loading group was the lower value than that of the control group. Similarly, the potassium concentration in serum was the lower value in salt loading group.
　The effect of salt loading on atrophy of the gastrocnemius was not seen in the salt loading groups. It seemed that salt loading might inhibit the degradation of muscle protein under muscle atrophy. It was concluded that salt loading influenced not only the control of the permeability, but also the inhibition of the degradation of protein. It was suggested that 1.8% salt loading group might inhibit the protein synthesis. The importance of the sodium chloride concentration equivalent to physiological saline solution in the muscle protein metabolism was suggested.

DESCENTE SPORTS SCIENCE Vol.7/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE