Morphological and functional changes in the skeletal muscles of the hind limbs in rats under enforced anaerobic physical exertion and allogeneic biomaterial application

Abstract

   Exhausting physical activity leads to sarcomere overstrain, destruction of the cell membrane, hydrolysis of structural proteins, thus, resulting in irreversible damage to muscle fibers. Allogeneic biomaterial (AB) is applied to regenerate various tissues and organs.   The aim of the study was to identify morphofunctional features of the skeletal muscle tissue after physical exertion and under AB application.   Material and methods. This experimental study involved male Wistar rats. Anaerobic physical exertion was simulated using the Porsolt test with a load equal 10 % of the body weight for 30 days. After training, animals of the main group (n = 10) were injected AB suspension: 4 ml of a 0.2 % solution into the muscles of the fore and hind limbs totally. Animals of the control group (n = 10) received physiological saline into similar zones. Tolerant load was investigated in 5 and 21 days after injection. Then the animals were withdrawn from the experiment, and muscles of the hind limbs were studied histologically, the total number, the average cross-sectional area of muscle fibers, and the number of necrotic fibers were measured.   Results. In 5 and 21 days animals from the control group manifested dystrophic changes in muscle fibers: type III, IV contractures, microcirculation disorders, mosaic necrosis of muscle fibers, inflammatory cell infiltration, and a decreased tolerant load. In 21 days fibrosis was detected. The AB introduction provided rhabdomyogenesis as soon as in 5 days. Inflammatory cell infiltration decreased, the polygonality of muscle fiber profiles was restored, and edematous phenomena were leveled. There was hyperplasia of muscle fibers, a decreased number of necrotic muscle fibers, inhibited fibrosis, and an increased tolerant load. AB further biodegraded.   Conclusion. AB contributed to the reduced manifestations of dystrophic changes in muscle fibers, strengthened actoprotective mechanism, and restored physical activity in the early stages.