Effect of immobilization on sole-plate and background cholinesterase of rat skeletal muscle

Abstract

The observation that the cholinesterase activity (ChE) of muscle decreases more profoundly during denervation atrophy than during non-neurogenic (disuse) atrophy has led to the suggestion that the nerve specifically regulates muscle ChE. However, denervation results in a flaccid paralysis in which the muscles are not used; therefore it is not justifiable to consider denervation and disuse atrophy as wholly separate entities. The present study was undertaken to investigate separately the changes in sole-plate and background ChE during disuse and denervation atrophy in order to determine whether the nerve specifically influences ChE at either of these sites. Disuse atrophy of the rat's soleus muscle was produced by internal fixation of the knee and ankle joints and denervation atrophy by transection of the sciatic nerve. With regard to protein loss, immobilization plus denervation produced greater atrophy (31.7%) than did immobilization alone (19.9%). The decrease in background ChE after each of these operations (35.6 and 22.4% respectively) was not significantly different from the loss in protein. Sole-plate ChE, on the other hand, exhibited a large decrease (53.4%) in response to denervation plus immobilization but was little altered by immobilization alone (8.7% decrease). Although the question of the specificity of the neural influence on background ChE remains unresolved by these results, it is concluded that the nerve specifically regulates ChE at the sole plate.