Exercise-induced improvement in the sensitivity of the rat soleus muscle to insulin is reversed by chloroadenosine--the adenosine receptor agonist.

The effect of 2-chloroadenosine on the sensitivity of the soleus muscle to insulin was measured after rats had been subjected to a single bout of exercise for 1 h at 20 m x min-1. An increased sensitivity of glycolysis to insulin measured in vitro by both lactate production and glucose transport was observed following the acute exercise. This process was reversed by the addition of 2-chloroadenosine, an adenosine receptor agonist, to the incubation medium. This agent had no effect on the exercise-induced increase in the sensitivity of glycogen synthesis to insulin in the same muscle preparation. Our findings confirm earlier studies suggesting that improved insulin sensitivity of glucose utilization by skeletal muscles after endurance exercise may be at least partly explained by an alteration in the adenosine concentration or changes in the properties of adenosine receptors in soleus muscle.