Reinnervation and regeneration of denervated rat soleus muscles

Muscle atrophy is a serious and sometimes irreversExperiments were approved by the University Committee on Use and Care of Animals. ible consequence of peripheral nerve damage.4 Recently, we found that muscle atrophy is reversible to Four groups of denervated muscles were used in this study. In all groups, the soleus muscles were varying extents when denervated muscles are grafted with nerve implants.4 In that study, rat extensor digdenervated for 2 months. In the first group, the muscles were denervated by cutting the sciatic nerve high itorum longus (EDL) muscles were denervated for 1–12 months. The muscles were then grafted into in the thigh region and then directing the cut ends of the nerve into nearby muscles. This method is innervated sites of host animals. The grafting operation resulted in a significant increase in mass and highly effective in maintaining the denervated state of the crural muscles.4 In the remaining three groups, force-generating ability of the muscles over the denervated state; the degree of improvement was inthe soleus muscles of each animal were locally denervated by the following procedure. The nerve versely proportional to the time of initial denervation. One question to arise from the study was branches innervating each soleus muscle were ligated, cut, and marked with powdered carbon. With whether or not grafting contributed to the functional return of the denervated muscles or if nerve implana needle attached to the ligating suture, the ligated end of the nerve branches was pulled through adjatation alone accounted for the return. To answer this, soleus muscles were denervated and then reincent muscles and then sutured to the lateral aspect of the biceps femoris. After 2 months, the first group nervated with and without concomitant grafting. The soleus, unlike the EDL, can be locally denervated of the locally denervated soleus muscles was removed for comparison with the soleus muscles that were and reinnervated without disturbing its tendons. This study found that 2-month denervated muscles grafted denervated by sciatic nerve section. with nerve implants have a higher mass and generate In the remaining two denervated groups, each sotwice the force of that generated by denervated musleus muscle was reinnervated by implanting its origicles which receive nerve implants but are not grafted. nal nerve into the muscle. Each nerve was cut free of its attachment to the biceps femoris and then imMETHODS planted into the soleus muscle with forceps. In one Experiments were performed on 34 highly inbred, of these two groups, the soleus muscles were orthoconventionally held, 3 1/2–4-month-old, male WI/ topically autografted prior to receiving nerve imHicksCar rats. The rats were anesthetized with ether plants. In the other group, the soleus muscles reduring surgery and sacrificed with ether overdose. ceived nerve implants but were not grafted. Controls of these groups were age-matched, normal intact soleus muscles. *Correspondence to: Dr. Lynn Billington Contract grant sponsor: NIH; Contract grant number: PO1 AG-10821 Physiology. Contractile property measurements CCC 0148-639X/97/060740-04  1997 John Wiley & Sons, Inc. were performed in vitro according to the methods