Repeated bouts of fast velocity eccentric contractions induce atrophy of gastrocnemius muscle in rats
Repeated bouts of fast velocity eccentric contractions induce atrophy of gastrocnemius muscle in rats
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DOI：
10.1007/s10974-015-9426-0
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发表时间：
2015-10-01
影响因子：
2.7
通讯作者：
Nakazato, Koichi
中科院分区：
文献类型：
--
作者：
Ochi, Eisuke;Nosaka, Kazunori;Nakazato, Koichi
一轮由快速偏心收缩组成的运动已被证明可以增加大鼠肌肉蛋白质的降解。本研究测试了这样的假设：四次快速偏心收缩后会诱发肌肉萎缩，但四次慢速偏心收缩后不会诱发肌肉萎缩。雄性Wistar大鼠随机分为3组；快速（180A 度/秒）速度（180EC，n = 7）、慢速（30A 度/秒）速度离心运动（30EC，n = 7）或假治疗组（对照组，n = 7）。 180EC和30EC组在肌肉诱发电刺激过程中通过伸展踝关节进行小腿三头肌离心收缩，每组4组5次，对照组每2 d进行扭矩测量，第四组后1 d处死所有大鼠。第四次训练后 1 天，180EC 组的腓肠肌内侧和外侧湿质量比对照组小 4-6%，内侧腓肠肌横截面积小 6-7%，小腿三头肌等长强直扭矩小 36% (p < 0.05)，但 30EC 和对照组之间没有明显差异。萎缩相关分子如 FoxO1、FoxO3 和肌肉生长抑制素的表达仅在 180EC 时上调 (78-229%)，但仅在 30EC 中第四次治疗后 1 天发现磷酸化 p70s6k (227%) 增加 (p < 0.05)。 180EC 中的促凋亡蛋白 Bax 水平高于对照 (p < 0.05)。这些结果支持这样的假设：肌肉因重复的快速而非慢速偏心收缩而萎缩。
One bout of exercise consisting of fast velocity eccentric contractions has been shown to increase muscle protein degradation in rats. The present study tested the hypothesis that muscle atrophy would be induced after four bouts of fast velocity eccentric contractions, but not after four bouts of slow velocity eccentric contractions. Male Wistar rats were randomly placed into 3 groups; fast (180A degrees/s) velocity (180EC, n = 7), slow (30A degrees/s) velocity eccentric exercise (30EC, n = 7), or sham-treatment group (control, n = 7). The 180EC and 30EC groups received 4 sessions of 4 sets of 5 eccentric contractions of triceps surae muscles by extending the ankle joint during evoked electrical stimulation of the muscles, and the control group had torque measures, every 2 days, and all rats were sacrificed 1 day after the fourth session. Medial and lateral gastrocnemius wet mass were 4-6 % smaller, cross-sectional area of medial gastrocnemius was 6-7 % smaller, and isometric tetanic torque of triceps surae muscles was 36 % smaller (p < 0.05) for 180EC than control at 1 day after the fourth session, but no such differences were evident between 30EC and control. The expressions of atrophy-related molecules such as FoxO1, FoxO3 and myostatin were upregulated (78-229 %) only for 180EC, but an increase in phosphorylated p70s6k (227 %) was found only for 30EC at 1 day after the fourth session (p < 0.05). The level of Bax, a pro-apoptotic protein, was greater (p < 0.05) for 180EC than control. These results support the hypothesis that muscles are atrophied by repeated bouts of fast but not slow velocity eccentric contractions.