Electrical stimulation of sciatic nerve of rats after partial denervation of soleus muscle

The purpose of this study was to determine the effect of electrical stimulation of the sciatic nerve on the recovery of the weight and tension of partially denervated rat soleus muscle. Electrodes were implanted unilaterally adjacent to the sciatic nerve in 30 adult female Wistar rats. Fifteen rats underwent bilateral partial nerve section (PNS) of the sciatic nerve to stimulate the plantar flexors. Both the normal and partially nerve sectioned animals were stimulated unilaterally with 4 ms, 2-4 mA current given at 10 pulses per second. Groups of five normal and five partially denervated animals were stimulated for two, four or eight hours per day, five days per week for six weeks. The soleus muscles were evaluated for muscle weight (MW), twitch (Pt) and tetanic (Po) tension, contraction time (CT) and fiber areas of the type 1 and type 2 fibers. The MW, Pt, Po, CT and area of the type 1 and 2 muscle fibers of the normal soleus muscles were 114 +/- 15 mg, 21 +/- 4 mg, 95 +/- 20 mg, 95 +/- 21 ms, 1532 +/- 84 microns m2 and 1267 +/- 136 microns m2 respectively. The electrical stimulation had no effect on the normal soleus muscles. The MW, Pt, Po, CT and area of type 1 and 2 muscles fibers of the partially denervated control soleus muscles were 59 +/- 12 mg, 9 +/- 4 mg, 22 +/- 14 mg, 104 +/- 32 ms, 1028 +/- 514 microns m2, and 849 +/- 292 microns m2 respectively. Two hours of electrical stimulation significantly increased the MW (87 +/- 17 g), Pt (17 +/- 6g), and Po (49 +/- 23 g) but not the type 1 and 2 fiber areas.(ABSTRACT TRUNCATED AT 250 WORDS)