ATP Causes Contraction of Denervated Skeletal Muscles

The ability of humoral agonists (and their persistent analogues) to induce contractions of denervated m. soleus and m. extensor digitorum longus of mice was investigated. Earlier, we found a change in the effectiveness of the ATP modulating effect under some non-physiological factors in the neuromuscular synapses of rodents. The aim of this study was to evaluate the effect of ATP on the contractility of isolated skeletal muscles of a mouse after traumatic denervation. It has been shown that 28-day denervation led to an increase in the strength of contractions of m. soleus and m. extensor digitorum longus caused by an acetylcholine analog. ATP application induced a contraction of denervated muscles, but not of intact ones. In the presence of a non-selective P2 receptor antagonist suramin, the effect of ATP ceased. We suggest that activation of post-synaptic P2X receptors of denervated muscles could cause their contraction. Apparently, this effect was 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.