Substances moved by axonal transport and released by nerve stimulation have an innervation-like effect on muscle.

Substances which have an innervation-like effect on the cholinesterase activity of organ-cultured rat extensor digitorum longus muscles are moved in nerve by axonal transport, are released from nerve by stimulation, and are present in innervated muscle but apparently absent from denervated muscle. Substances which increase the acetylcholine sensitivity of cultured muscles behave similarly.