Morphology and histochemistry of the soleus muscle from normal and exercised rats

Publisher Website
Google Scholar
Abstract
Sixty white rats were divided into three groups which consisted of (1) rats individually housed in cages having dimensions of 24 × 18 × 18 cm, (2) rats housed in similar cages and forced to swim for 30 minutes a day with a weight equal to 3% of body weight, and (3) rats housed in individual cages equipped with a revolving drum permitting each rat to exercise at will. The third group was also forced to swim for two 30‐minute periods each day with a weight equal to 4% of body weight attached to the tip of the tail. The experimental treatments lasted for a period of 52 days. The rats were exercised six days per week. The day after the final treatment, the left soleus, plantaris and gastrocnemius muscles were removed, frozen, and serial sections treated with a variety of histochemical and histological procedures.Necrotic, angular and split fibers were observed in the soleus muscle but not the gastrocnemius and plantaris of sedentary, moderately exercised and heavily exercised rats. These features were characteristic of the seemingly normal soleus of sedentary and chronically exercised rats and were not manifestations of any apparent myopathy. No difference was found in the number of fibers that were longitudinally split. However, the number of fibers (“subfibers”) resulting from split fibers was greater in the moderately exercised than in the sedentary rats, but greatest in the heavily exercised group.