ATP Causes Contraction of Denervated Skeletal Muscles

Abstract

In this work we investigated the ability of humoral agonists (and their stable analogues) to induce contractions in mouse denervated m. soleus and m. EDL. Previously, we had found a change in the effectiveness of the modulating effect of ATP under the influence of some non-physiological factors in the neuromuscular synapses of rodents. The aim of this study is to evaluate the effect of ATP on the contractility of isolated skeletal muscles of mice after traumatic denervation. It was shown that 28-day denervation led to an increase in the strength of contractions of m. soleus and m. EDL induced by an acetylcholine analog. The application of ATP caused the contraction of denervated but not intact muscles. In the presence of a non-selective antagonist of the P2 receptors suramin, the effect of ATP ceased. We assume that the observed ATP-induced contraction can be accounted for by activation of postsynaptic P2X receptors in denervated muscles. Apparently, this effect is caused by an increase in the expression of postsynaptic receptors in response to a violation of neurotrophic control and the conductive ability of the nerve fiber.