Joumaa W H, Serrurier B, Bigard X, Léoty C
Laboratoire de Physiologie Générale, CNRS UMR 6018, Faculté des Sciences et des Techniques, Université de Nantes, Nantes, France.
Acta Physiol Scand. 2002 Jul;175(3):189-99. doi: 10.1046/j.1365-201X.2002.00988.x.
This investigation was designed to examine whether short-term administration of anabolic-androgenic steroids (AAS) (nandrolone decanoate) could produce changes in contractile responses of untrained rat fast- (edl) and slow- (soleus) twitch skeletal muscle. Twenty male rats were divided into two groups, one group received weekly (for 6 weeks) an intramuscular injection of AAS, nandrolone decanoate (15 mg kg(-1)) and the second group received weekly the similar doses of vehicle (sterile peanut oil). In edl intact isolated small bundles (two to four cells), it was found that nandrolone decanoate treatment increases the K+ contracture tension (146 mM) relative to maximum tension by 56%, whereas no change was observed in the time to peak tension and in the time constant of relaxation. By contrast, in treated soleus muscle, compared with control, no significant modification was found in the K+ contracture characteristics. The change in edl contractile responses was associated with a shift to more negative potential of the voltage-dependence activation and the steady-state inactivation curves which also shifted leftward in treated soleus fibres. Furthermore, in edl skinned Triton X-100 fibres, the Ca2+ sensitivity of contractile proteins (pCa50) was increased, while electrophoresis analysis indicates no significant effect of nandrolone decanoate treatment on myosin heavy chain (MHC) isoforms. The present results show that nandrolone decanoate treatment produces more pronounced changes in untrained fast muscle function rather than soleus by acting at different levels of the excitation-contraction coupling mechanism without changes in the MHC isoforms and that contractile responses became similar to those found in soleus muscle.
本研究旨在探讨短期给予合成代谢雄激素类固醇（AAS）（癸酸诺龙）是否会引起未训练大鼠快肌（趾长伸肌）和慢肌（比目鱼肌）收缩反应的变化。将20只雄性大鼠分为两组，一组每周（共6周）肌肉注射AAS癸酸诺龙（15 mg·kg⁻¹），另一组每周注射相同剂量的溶剂（无菌花生油）。在完整分离的趾长伸肌小束（2 - 4个细胞）中，发现癸酸诺龙处理使K⁺挛缩张力（146 mM）相对于最大张力增加了56%，而达到峰值张力的时间和松弛时间常数未观察到变化。相比之下，在处理后的比目鱼肌中，与对照组相比，K⁺挛缩特征未发现显著改变。趾长伸肌收缩反应的变化与电压依赖性激活和稳态失活曲线向更负电位的偏移有关，处理后的比目鱼肌纤维中这些曲线也向左移动。此外，在经Triton X - 100处理的趾长伸肌脱膜纤维中，收缩蛋白的Ca²⁺敏感性（pCa50）增加，而电泳分析表明癸酸诺龙处理对肌球蛋白重链（MHC）亚型没有显著影响。目前的结果表明，癸酸诺龙处理通过作用于兴奋 - 收缩偶联机制的不同水平，在未训练的快肌功能中产生比在比目鱼肌中更明显的变化，且MHC亚型没有改变，并且收缩反应变得类似于在比目鱼肌中发现的反应。
