Plant D R, Gregorevic P, Williams D A, Lynch G S
Department of Physiology, The University of Melbourne, Victoria 3010, Australia.
J Appl Physiol (1985). 2001 Mar;90(3):832-8. doi: 10.1152/jappl.2001.90.3.832.
We used intact fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus muscles from rats and mice to test the hypothesis that exogenous application of an oxidant would increase maximum isometric force production (P(o)) of slow-twitch muscles to a greater extent than fast-twitch skeletal muscles. Exposure to an oxidant, hydrogen peroxide (H(2)O(2); 100 microM to 5 mM, 30 min), affected P(o) of rat muscles in a time- and dose-dependent manner. P(o) of rat soleus muscles was increased by 8 +/- 1 (SE) and 14 +/- 1% (P < 0.01) after incubation with 1 and 5 mM H(2)O(2), respectively, whereas in mouse soleus muscles P(o) was only increased after incubation with 500 microM H(2)O(2). P(o) of rat EDL muscles was affected by H(2)O(2) biphasically; initially there was a small increase (3 +/- 1%), but then P(o) diminished significantly after 30 min of treatment. In contrast, all concentrations of H(2)O(2) tested decreased P(o) of mouse EDL muscles. A reductant, dithiothreitol (DTT; rat = 10 mM, mouse = 1 mM), was added to quench H(2)O(2), and it reversed the potentiation in P(o) in rat soleus but not in rat EDL muscles or in any H(2)O(2)-treated mouse muscles. After prolonged equilibration (30 min) with 5 mM H(2)O(2) without prior activation, P(o) was potentiated in rat soleus but not EDL muscles, demonstrating that the effect of oxidation in the soleus muscles was also dependent on the activation history of the muscle. The results of these experiments demonstrate that P(o) of both slow- and fast-twitch muscles from rats and mice is modified by redox modulation, indicating that maximum P(o) of mammalian skeletal muscles is dependent on oxidation.
我们使用大鼠和小鼠完整的快肌趾长伸肌（EDL）和慢肌比目鱼肌来验证以下假设：外源施加氧化剂时，慢肌比目鱼肌最大等长力产生（P(o)）的增加幅度将大于快肌骨骼肌。暴露于氧化剂过氧化氢（H(2)O(2)；100 microM至5 mM，30分钟）后，大鼠肌肉的P(o)呈现出时间和剂量依赖性变化。与1 mM和5 mM H(2)O(2)孵育后，大鼠比目鱼肌的P(o)分别增加了8±1（SE）和14±1%（P<0.01），而在小鼠比目鱼肌中，仅在与500 microM H(2)O(2)孵育后P(o)才增加。大鼠EDL肌肉的P(o)受H(2)O(2)影响呈双相变化；最初有小幅增加（3±1%），但处理30分钟后P(o)显著下降。相反，所有测试浓度的H(2)O(2)均降低了小鼠EDL肌肉的P(o)。添加还原剂二硫苏糖醇（DTT；大鼠为10 mM，小鼠为1 mM）以淬灭H(2)O(2)，它逆转了大鼠比目鱼肌P(o)的增强，但对大鼠EDL肌肉或任何经H(2)O(2)处理的小鼠肌肉均无此作用。在未预先激活的情况下，与5 mM H(2)O(2)长时间平衡（30分钟）后，大鼠比目鱼肌的P(o)增强，但EDL肌肉未增强，这表明比目鱼肌中的氧化作用也取决于肌肉的激活历史。这些实验结果表明，大鼠和小鼠的慢肌和快肌的P(o)都可通过氧化还原调节进行改变，这表明哺乳动物骨骼肌的最大P(o)取决于氧化作用。
