Changes in cholinesterase activity of rat muscle during growth and hypertrophy

Abstract

Cholinesterase (ChE) activity has been quantitatively measured in skeletal muscle of rats to determine the changes that occur during growth and hypertrophy. Sections of muscle were stained histochemically or assayed quantitatively for ChE. ChE associated with sole plates was distinguished from nonsole-plate (or background) ChE by comparing regions of muscle having sole plates with regions lacking them. During growth, the body weight and the wet weight of the sternomastoid muscle increased proportionally. As the muscle became heavier, the background ChE activity increased but the sole-plate ChE remained constant. During hypertrophy of the soleus and plantaris (induced by severing the gastrocnemius from the Achilles tendon), the ChE and protein both increased rapidly and at the same rate, so that the specific activity (ChE/mg protein) remained constant. The results are discussed in terms of a dual regulation of ChE activity by neural and muscular factors.