Relationship between extensibility and collagen expression in immobilized rat skeletal muscle

ABSTRACT Introduction This study investigated longitudinal changes in muscle extension and collagen expression in an immobilized rat soleus muscle, and assessed the relationship between both elements. Methods Soleus muscles of the control and immobilization groups (1, 2, 4, 8, and 12 weeks) were used for analysis of muscle extensibility and collagen expression. Results The slope value/physiological cross‐sectional area (PCSA; a parameter for muscle extensibility) and hydroxyproline (a parameter for collagen expression) were significantly higher in the immobilization group than in the control group for all experimental time points. In the immobilization group, both factors were significantly higher at 4, 8, and 12 weeks than at 1 and 2 weeks after immobilization. A significant positive correlation was observed between the slope value/PCSA and hydroxyproline expression. Discussion The present study indicated that a decrease in muscle extensibility depended on collagen overexpression in immobilized rat soleus muscles. Muscle Nerve 57: 672–678, 2018