Regeneration of the tibialis anterior muscle at different times following injury induced by neuromuscular electrical stimulation

• Published in: Revista brasileira de fisioterapia (São Carlos (São Paulo, Brazil)) Brazil)), 2007-04, Vol.11 (2), p.99-104
• Main Authors: Botelho, AP, Facio, F A, Minamoto, V B
• Format: Article
• Language: Portuguese
• ISSN: 1413-3555

Background: Skeletal muscle injuries may be caused by contraction of the muscle concerned. Objective: To analyze the tibialis anterior muscle at different times following injury induced by electrical stimulation. Method: Male Wistar rats (298.2 plus or minus 16.0g) were divided into two electrically stimulated groups evaluated after three and five days (n= 20) and two control groups, also evaluated after three and five days (n= 14). While stretched, the tibialis anterior muscle was injured by neuromuscular electrical stimulation (90 minutes, 30 Hz, 1 m/s, Ton/Toff 4 s and 4 mA). Three and five days afterwards, the animals were sacrificed and the muscles were removed. Histological sections were cut (10 mu m) using a cryostat and were stained with toluidine blue. The body and muscle weights were statistically analyzed using Student's t test (p less than or equal to 0.05). Results: The final body weight was higher than the initial weight for the 3-day control group (288.5 plus or minus 18.3g vs. 308.5 plus or minus 24.3g) and 5-day control group (288.4 plus or minus 15.0g vs. 305.5 plus or minus 20.7g) and lower for the 3-day stimulated group (305.0 plus or minus 13.0g vs. 285.6 plus or minus 13.2g) and 5-day stimulated group (306.1 plus or minus 12.4g vs. 278.4 plus or minus 20.9g). The relative muscle weight in the 5-day stimulated group was lower than in the 5-day control group (0.20 plus or minus 0.001% vs. 0.22 plus or minus 0.01%, respectively). The histological analysis showed variance between the animals regarding the extent and signs of fiber damage and/or regeneration, and the distal region was the most injured. The 3-day stimulated group presented predominance of cell infiltrate and myofilament hypercontraction, while the 5-day stimulated group presented predominance of cell infiltrate, basophils and fibrosis. Conclusion: A period of two days following electrical stimulation was sufficient for showing a difference in the regeneration process. The distal region of the tibialis anterior muscle was more susceptible to injury.