Nerve supply and experimental myotonia in rats.

20, 25-Diazacholesterol does not induce myotonia in denervated mammalian skeletal muscle, and cordotomy also renders the muscles resistant to the induction of myotonia. Denervation of muscle already rendered myotonic, has no effect on the intensity of the phenomenon. Finally, tenotomy and posterior rhizotomy leave the myotonic activity in the "deafferentated" muscles unchanged. These findings are discussed in relation to "trophic" influences of the motor pathways on the postsynaptic structures of skeletal muscle.