Effects of ATP on Time Parameters of Contractility of Rats’ Slow and Fast Skeletal Muscles in Normal and Hypothermic Conditions

We have previously shown that hypothermia leads to an increase in the synaptic modulating effects of ATP but not adenosine several different animal skeletal muscles. In this paper, we studied effect on amplitude–time parameters single and tetanic contractions rats’ isolated fast (1) slow (2) muscles at temperatures. found when were stimulated by electrical field (0.1 Hz, 0.5 ms, 10 V), with a decrease bath temperature from 37 °C 14 (3), there was half-relaxation time muscle (m. soleus), EDL). Similar observed using carbachol-induced contraction technique, which suggests postsynaptic (4) nature expansion contractile response induced (5). To confirm phenomenon, experiments performed high calcium level (7.2 mM), presynaptic be offset. hypercalcium condition did significantly change measured both record contractions, gradually increased frequency impulses increment 2.5 Hz achieve fusion frequencies 12.5 for m. soleus 17.5 EDL normal (100 μM) decreased parameter 5 without affecting muscle. conclude potentiates hypothermia-induced slow, fast, acting P2 receptors (6).