Department of Functional Morphology, University of Tartu, Estonia.
Int J Sports Med. 2011 Apr;32(4):247-53. doi: 10.1055/s-0030-1270513. Epub 2011 Mar 4.
The aim of the study was to elucidate the effect of unloading and reloading on the collagen expression and synthesis rate of myofibrillar proteins in fast-twitch (FT) muscle in relation to changes in muscle strength and motor activity. Northern blot analysis was used for testing the specificity of cDNA probes and protein synthesis rate was measured according to incorporation of radioactive leucine into different protein fractions. Unloading depresses collagen type I and III (p<0.001), type IV (p<0.05) and reloading enhances collagen expression in fast-twitch skeletal muscle in comparison with unloading. Enhanced expression of matrix metalloproteinase-2 continued during the first week of reloading (p<0.01) and tissue inhibitor of metalloproteinase-2 during reloading (p<0.05). Changes in collagen expression in FT muscle are in good agreement with changes in myofibrillar protein synthesis during unloading and reloading. In conclusion alterations in extracellular matrix and myofibrillar apparatus in FT skeletal muscle are related to changes in muscle strength and motor activity, are significant in exercise training and determination of recovery periods in the training process as well as in athletes' rehabilitation.
本研究旨在阐明去负荷和再负荷对快肌（FT）肌肉中胶原蛋白表达和肌球蛋白蛋白合成率的影响，以及与肌肉力量和运动活动变化的关系。采用 Northern blot 分析来检测 cDNA 探针的特异性，并根据放射性亮氨酸掺入不同蛋白部分来测量蛋白合成率。与去负荷相比，再负荷会降低 I 型和 III 型胶原蛋白（p<0.001）、IV 型胶原蛋白（p<0.05）的表达，增强快肌骨骼肌肉中的胶原蛋白表达。基质金属蛋白酶-2 的表达在再负荷的第一周持续增加（p<0.01），组织金属蛋白酶抑制剂-2 在再负荷期间增加（p<0.05）。FT 肌肉中胶原蛋白表达的变化与去负荷和再负荷过程中肌球蛋白蛋白合成的变化一致。总之，FT 骨骼肌细胞外基质和肌球蛋白装置的改变与肌肉力量和运动活动的变化有关，在运动训练以及训练过程中恢复时间的确定以及运动员康复中具有重要意义。
