A High Calcium Level-Based Model for Identifying Postsynaptic Effects of ATP

Identification of the pre- and postsynaptic effects of ATP is a methodological challenge. In our previous study, the role of P2 receptor signaling in synaptic transmission processes was evaluated using carbachol-induced skeletal muscle contractions. The search for models that can record the postsynaptic side of purinergic signaling during the application of electrical stimulation led to the idea of controlling the presynaptic terminal of ATP-mediated modulation. In in vitro experiments, electromyograms and mechanomyograms during isometric contractions of isolated nerve-muscle preparations of rat soleus and extensor digitorum longus (EDL) muscles revealed postsynaptic effects of ATP in the presence of a high intracellular calcium level. Thus, the effects of ATP in the presence of increased Ca 2+ content were seen through contraction of soleus muscles that started to contract quicker by fifty percent and inhibition of contractility of EDL muscles; this was in accord with data obtained earlier on carbachol-induced contractions. We have demonstrated an ATP-dependent processes in the postsynaptic site that may contribute significantly to adaptation mechanisms in hypothermia.