Past injurious exercise attenuates activation of primary calcium-dependent injury pathways in skeletal muscle during subsequent exercise.
Past injurious exercise attenuates activation of primary calcium-dependent injury pathways in skeletal muscle during subsequent exercise.
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DOI：
10.14814/phy2.13660
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发表时间：
2018-03
影响因子：
2.5
通讯作者：
Ishii N
中科院分区：
文献类型：
--
作者：
Takagi R;Ogasawara R;Takegaki J;Tamura Y;Tsutaki A;Nakazato K;Ishii N
过去收缩引起的骨骼肌损伤降低了随后的损伤程度；这种现象被称为“反复发作效应（RBE）”。本研究探讨了RBE的潜在机制，重点关注主要的钙依赖性损伤途径。Wistar大鼠又分为单次损伤组（SI）和重复损伤组（RI）。10周龄时，RI组每只大鼠右腓肠肌发生剧烈偏心收缩（ECs）。随后，两组大鼠均于14周龄时在同一肌肉上施加轻度ECs。运动后1天，RI组的强度赤字低于SI组，两组均未表现出膜通透性增加。14周龄给予ECs后，蛋白羰基浓度和总钙蛋白酶活性均升高。尽管如此，这些增加在RI组低于SI组。此外，与SI组相比，RI组钙依赖性calpain - 1和calpain - 3的自溶减少。尽管两组在14周龄ECs期间的峰值踝关节扭矩和总力产生相似，但RI组的JNK （Thr183/Tyr185）磷酸化水平低于SI组，JNK是施加在肌肉上的机械应力的指标。这些发现表明，初级钙依赖性损伤通路的激活被过去的损伤性运动减弱，并且在ECs期间施加在肌肉纤维上的机械应力可能会在RBE中减少。
Past contraction‐induced skeletal muscle injury reduces the degree of subsequent injury; this phenomenon is called the “repeated bout effect (RBE).” This study addresses the mechanisms underlying the RBE, focusing on primary calcium‐dependent injury pathways. Wistar rats were subdivided into single injury (SI) and repeated injury (RI) groups. At age 10 weeks, the right gastrocnemius muscle in each rat in the RI group was subjected to strenuous eccentric contractions (ECs). Subsequently, mild ECs were imposed on the same muscle of each rat at 14 weeks of age in both groups. One day after the exercise, the RI group showed a lower strength deficit than did the SI group, and neither group manifested any increase in membrane permeability. The concentration of protein carbonyls and activation of total calpain increased after ECs given at the age of 14 weeks. Nonetheless, these increases were lower in the RI group than in the SI group. Furthermore, calcium‐dependent autolysis of calpain‐1 and calpain‐3 in the RI group was diminished as compared with that in the SI group. Although peak ankle joint torque and total force generation during ECs at the age of 14 weeks were similar between the two groups, phosphorylation of JNK (Thr183/Tyr185), an indicator of mechanical stress applied to a muscle, was lower in the RI group than in the SI group. These findings suggest that activation of the primary calcium‐dependent injury pathways is attenuated by past injurious exercise, and mechanical stress applied to muscle fibers during ECs may decrease in the RBE.