Decrease in mass of slow and fast tenotomized muscles of guinea pigs: role of nerve impulses and neurogenic factors.

The role of nerve impulses and neurogenic factors in the decrease in muscle mass following tenotomy was investigated in 30 adult (15 males, 15 females) guinea pigs. Unilateral tenotomy, neurectomy and simultaneous tenotomy and neurectomy of slow and fast hindlimb muscles were performed in 3 groups respectively. Each group comprised 10 guinea pigs. The unoperated hindlimb of each animal in each group served as control. The weight loss occurred in both slow and fast muscles but was greater in the slow soleus muscle as compared to the fast gastrocnemius muscle. In each muscle the weight loss was least in the tenotomized group. This was followed by the weight loss in the neurectomized group. The greatest weight loss was observed in the simultaneously tenotomized and neurectomized group. These observations agree with the suggestion of other workers that a possible neurogenic factor flowing from the nerves to the muscles was very significant in maintenance of muscle fibre stability. It indicated also that simultaneous neurectomy and tenotomy did not prevent degenerative changes in slow and fast muscles and that it was not nerve impulses reaching the tenotomized muscles that were responsible for degenerative changes observed but that other factors were responsible.