NOCICEPTIVE ATROPHY OF THE RAT SOLEUS MUSCLE INDUCED BY BONE-FRACTURE- A MORPHOMETRIC STUDY

Reflex atrophy of the soleus muscle induced by ipsilateral metatarsal bone fracture in Sagatal-anesthetized adult male rats was studied by u sing two-dimensional stereological methods 7 days after the operation. When compared with contralateral solei, the wet weight of the experim ental soleus muscles was decreased by similar to 246 and the area of t he entire muscle section by similar to 29%. In atrophied solei, the nu mber of type 1 fibers was lower by similar to 8%, resulting in lower t otal number of fibers (by similar to 6%). This indicates that slow mot or units might be more sensitive to nociceptive stimulation. However, with respect to the fiber area, the reflex atrophy induced by metatars al bone fracture in the rat soleus muscle resembles simple atrophy aft er 7 days, as the mean muscle fiber area was decreased by similar to 2 6% with no significant difference between atrophy in type 1 and type 2 a fibers (by 27.3 and 23.0%, respectively).