Glycogenolytic effect of adrenaline in skeletal muscle of rats adapted to endurance exercise

Abstract

Rats were adapted to endurance exercise (swimming) for six weeks. During the training program each rat swum totally for 108 hours. It was found that the training applied reduced markedly glycogenolytic effect of adrenaline (0.1 mg/kg) in each of the examined type of muscle (the white, red and intermediate ones). The reduction of the glycogenolytic effect of adrenaline in the trained rats was less pronounced in the intermediate muscle than in the other two muscles. The hyperglycemic effect of adrenaline was also reduced in the trained group. It is concluded that the decreased reactivity of glycogenolytic system in skeletal muscles to adrenaline could be partly responsible for the slower rate of the intramuscular glycogen mobilization during exercise in the trained individuals.