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Regenerated rat skeletal muscle after periodic contusions

By V.B. Minamoto, S.R. Bunho and T.F. Salvini


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

Topics: skeletal muscle, periodic contusion, long-term regeneration, rat, Biology (General), QH301-705.5, Science, Q, DOAJ:Biology, DOAJ:Biology and Life Sciences, Medicine (General), R5-920, Medicine, R, DOAJ:Medicine (General), DOAJ:Health Sciences
Publisher: Associação Brasileira de Divulgação Científica
Year: 2001
DOI identifier: 10.1590/S0100-879X2001001100012
OAI identifier: oai:doaj.org/article:4476a7fe38f5423b892be847c27764aa
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