Effects of ATP and adenosine on contraction amplitude of rat soleus muscle at different temperatures

Introduction: The aim of this study was to evaluate the effects of adenosine 5-triphosphate (ATP) and adenosine on the contractility of mammalian skeletal muscle under hypothermic conditions. Methods: Contractions of isolated rat soleus muscle were induced by either electrical stimulation (ES) or carbachol at physiological temperatures (37 degrees C) and hypothermic conditions (30-14 degrees C) and recorded in the presence of ATP, adenosine, suramin, and 8-(p-sulfophenyl)-theophylline (8-SPT). Results: At 37 degrees C, incubation of the muscles with ATP inhibited ES-induced contractions; the inhibitory effect of ATP disappeared at 14 degrees C. Adenosine inhibited ES-induced contractions at all temperature levels; 8-SPT fully prevented the action of adenosine. ATP and adenosine did not significantly affect carbachol-induced contractions at 37 degrees C, while at lower temperatures ATP potentiated them. Suramin fully prevented effects of ATP. Conclusions: ATP is involved in both pre- and postsynaptic regulation of rat soleus muscle contractility, and these processes are significantly more pronounced at low temperatures. Muscle Nerve55: 417-423, 2017