The effects of denervation on contractile properties or XXXX skeletal muscle.

@entity129 @entity2701 @entity194 @entity35 @entity116
1. Isometric contractions of fast and slow twitch muscles of @entity35 were recorded 1-42 days after denervation. 2. The major changes occurred over the period from 2 to 6 days after denervation. These changes were qualitatively similar in the two types of muscle. The most important effects were on the twitch: times to peak and half relaxation were prolonged, active @entity2701 and peak rate of rise of @entity2701 were increased. Tetanic @entity2701 per unit cross-sectional area and the maximum rate of rise of @entity2701 decreased during this period but, in the second week, the @entity2701 recovered substantially and the maximum rate recovered completely. 3. Very small differences were seen between muscles denervated with @entity129 at day 4. 4. In the late stage of denervation (7-42 days) twitch and tetanic @entity2701 fell more than cross-sectional area, but this may have been due to greater @entity194 of fibres compared with other muscle tissue. 5. Apart from this @entity2701 fall, there were only small changes in the fast muscle in the late stage of denervation. These were a fall in twitch- @entity116 ratio and a prolongation of relaxation. 6. In more than half of the soleus muscles there was a late reversal of some of the denervation changes, and these muscles showed a greater degree of @entity194 . The less atrophied soleus muscles maintained a prolonged twitch and a low rate of development of @entity2701 . 7. It is concluded that denervation affects the contractile properties of muscle as early and as abruptly as it does the membrane properties, and that most of the contractile changes are a direct consequence of changes in excitation-contraction coupling alone.
