Effects of Immobilization and Activity on Neuromuscular Regeneration

This report is concerned with the results of experiments dealing with the effects of various conditions on the extent and rate of neuromuscular atrophy and regeneration. These include such conditions as immobilization of the limb by casts, forced exercise, electrical stimulation of the paralyzed muscle, application of cold and heat and attempts to enhance functional reinnervation through facilitation of axon bifurcation. Most of the experiments were carried out on the gastrocnemius muscles and tibial nerves of adult albino rats and included quantitative measurements of muscle mass, strength and creatine content. Complete paralysis of the gastrocnemius was produced by crushing the tibial at the level of its junction with the peroneal. Partial paralysis was produced by removing a section of one or more of the spinal nerves contributing motor fibers to this muscle. Quantitative studies were made as to the condition of the muscles and nerves at designated times after either