The effects of ATP on the contractions of rat and mouse fast skeletal muscle.

Introduction: The aim of this study was to compare the effects of adenosine-5'-triphosphate (ATP) and adenosine on the contractility of rodent extensor digitorum longus (EDL) muscle at normal and low temperatures.

Methods: Contractions of rat and mouse isolated EDL were induced by either electrical stimulation (ES) or exogenous carbachol and recorded in the presence of ATP or adenosine (both at 100 μM).

Results: ATP at all temperatures caused a decrease of the contractions induced by carbachol in rat and mouse EDL and ES-induced contractions in rat EDL, while it potentiated the ES-induced contractions of mouse EDL.

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°C) and hypothermic conditions (30-14°C) and recorded in the presence of ATP, adenosine, suramin, and 8-(p-sulfophenyl)-theophylline (8-SPT).

Results: At 37°C, incubation of the muscles with ATP inhibited ES-induced contractions; the inhibitory effect of ATP disappeared at 14°C.