Motor unit properties in the soleus muscle after its distal tendon transfer to the plantaris muscle tendon in the rat.

Abstract : The aim of this study was to evaluate how a modification in the mechanical conditions under which a muscle is used could induce changes in the characteristics and the spinal drive of its motor units (MU). The distal tendon of the soleus muscle of Wistar rats was transferred to the distal stump of the plantaris muscle tendon. The EMG activity of the soleus was chronically recorded for 8 weeks, every other day, during a 1-min treadmill walk. After spinal ventral root splitting, individual MU contractile properties were measured in control soleus (102 MUs) or in transposed soleus muscles after 4 weeks (41 MUs) or 8 weeks (28 MUs). Muscle/body weight ratio did not vary after transposition, nor did MU tetanic forces. A decrease in MU twitch contraction times and in their half relaxation times was observed at weeks 4 and 8. MU tension-frequency curves varied significantly after tendon transfer, becoming closer to the curves of the fast MUs of the control group. During locomotion, we observed no change in the amplitude of rectified-filtered electromyographic activity, but a significant decrease in mean burst duration and an increase in the median frequency of the power density spectrum. Tendon transposition of the soleus muscle brought about adaptations in MU contractile properties and soleus spinal control.
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Journal of Physiology, Wiley, 2003, 553 (Pt 3), pp.925-33. 〈10.1113/jphysiol.2003.048389〉
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Soumis le : mercredi 27 mars 2013 - 23:07:34
Dernière modification le : jeudi 13 septembre 2018 - 15:17:14

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Marie-Agnès Giroux-Metges, Jean-Pierre Pennec, Julien Petit, Christelle Goanvec, Germaine Dorange, et al.. Motor unit properties in the soleus muscle after its distal tendon transfer to the plantaris muscle tendon in the rat.. Journal of Physiology, Wiley, 2003, 553 (Pt 3), pp.925-33. 〈10.1113/jphysiol.2003.048389〉. 〈hal-00805464〉

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