[Effect of protein synthesis inhibitors on the development of denervation-like changes in the frog muscle fiber membrane after colchicine-induced blockade of axoplasmic transport]

Abstract

Experiments on frogs were made to study denervation-like changes in the properties of muscle fiber membrane produced by axoplasmic transport blockade with colchicine. Injection into the animals of the protein synthesis inhibitors, actinomycin D or puromycin, in conjunction with colchicine application to the nerve prevented the appearance of extrajunctional sensitivity to acetylcholine, but did not affect the denervation-like decrease of resting membrane potential, increase in input resistance, and time constant of the muscle fiber membrane. The evidence obtained supports the ideas on the participation of the substances supplied to the muscle with axonal transport in the neurotrophic control of the skeletal muscles. Besides, it attest to the existence of an independent control over chemosensitivity and electrogenesis on the muscle membrane. The results of applying the protein synthesis inhibitors indicate a possibility of neuronal regulation of the synthesis of cholinoreceptors at the transcriptional level. In this case the appearance of extrajunctional sensitivity to acetylcholine after axotransport blockade with colchicine and after denervation is most likely due to the synthesis of new cholinoreceptors rather than by their lateral diffusion from the junctional zone.