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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Regenerated rat skeletal muscle after periodic contusions

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Author(s):
V.B. Minamoto [1] ; S.R. Bunho [2] ; T.F. Salvini [3]
Total Authors: 3
Affiliation:
[1] Universidade Federal de São Carlos. Departamento de Fisioterapia. Unidade de Plasticidade Muscular - Brasil
[2] Universidade Federal de São Carlos. Departamento de Fisioterapia. Unidade de Plasticidade Muscular - Brasil
[3] Universidade Federal de São Carlos. Departamento de Fisioterapia. Unidade de Plasticidade Muscular - Brasil
Total Affiliations: 3
Document type: Journal article
Source: Brazilian Journal of Medical and Biological Research; v. 34, n. 11, p. 1447-1452, 2001-11-00.
Abstract

In the present study we evaluated the morphological aspect and changes in the area and incidence of muscle fiber types of long-term regenerated rat tibialis anterior (TA) muscle previously submitted to periodic contusions. Animals received eight consecutive traumas: one trauma per week, for eight weeks, and were evaluated one (N = 8) and four (N = 9) months after the last contusion. Serial cross-sections were evaluated by toluidine blue staining, acid phosphatase and myosin ATPase reactions. The weight of injured muscles was decreased compared to the contralateral intact one (one month: 0.77 ± 0.15 vs 0.91 ± 0.09 g, P = 0.03; four months: 0.79 ± 0.14 vs 1.02 ± 0.07 g, P = 0.0007, respectively) and showed abundant presence of split fibers and fibers with centralized nuclei, mainly in the deep portion. Damaged muscles presented a higher incidence of undifferentiated fibers when compared to the intact one (one month: 3.4 ± 2.1 vs 0.5 ± 0.3%, P = 0.006; four months: 2.3 ± 1.6 vs 0.3 ± 0.3%, P = 0.007, respectively). Injured TA evaluated one month later showed a decreased area of muscle fibers when compared to the intact one (P = 0.003). Thus, we conclude that: a) muscle fibers were damaged mainly in the deep portion, probably because they were compressed against the tibia; b) periodic contusions in the TA muscle did not change the percentage of type I and II muscle fibers; c) periodically injured TA muscles took four months to reach a muscle fiber area similar to that of the intact muscle. (AU)