[Effect of actinomycin D on the post-denervational changes of chemosensitivity in muscle spindles in the cat].

The effect of preliminary injection of the inhibitor of protein synthesis actinomycin D on development of extrajunctional cholinergic receptors in denervated intrafusal muscle in cats, was investigated. Chronic motor denervation of the soleus muscle (3-5 days after denervation) caused supersensitivity of intrafusal muscle fibres to acetylcholine (Ah), subecholine (SCh) and succinylcholine (Sh). Injections of actinomycin D prevented the supersensitivity, the latter being dependent on the synthesis of new cholinoreceptors and their incorporation in the extrajunctional region of intrafusal fibres.