Induction of acetylcholine receptors in muscle cultures

Acetylcholine receptors in muscle cells differentiated in vitro were monitored by using¹²⁵I-α-bungarotoxin. The number of cholinergic receptors was increased 4-8 fold in 2 days due to inhibition of spontaneous contraction of the muscle fibers. The inhibition of this activity, whether mediated through tetrodotoxin, lidocaine or D-600, did not affect the biochemical differentiation of muscle, as represented by creatine-phosphokinase and acetylcholinesterase activity. "Induction" of receptors by tetrodotoxin was inhibited by cycloheximide, actinomycin-D, or 5-bromotubercidine. Dystrophic muscle responded in vitro to inhibition of contraction similar to normal tissue.