[Effect of noradrenaline and serotonin on glycogen metabolism in rat tissues]

Effects of biogenic amines--noradrenaline and serotonin--on phosphorylase, acid alpha-glucosidase (gamma-amilase), glycogen synthetase as well as on content of glycogen in rat liver tissue, heart and skeletal muscles were studied in vivo. Administration of noradrenaline and serotonin led to activation of phosphorylase in liver tissue, heart and skeletal muscles. Noradrenaline, administered into rats, caused a decrease in activity of acid alpha-glucosidase in heart and liver tissues and did not affect the enzymatic activity in skeletal muscles. Serotonin did not cause any effect on the activity of acid alpha-glucosidase in all the tissues studied. After administration of both amines inhibition of glycogen synthetase occurred in heart muscle, whereas the enzymatic activity was unaltered in skeletal muscles and liver tissue. Content of glycogen was decreased in heart muscle of the rats in which noradrenaline was administered. Content of glycogen was increased after serotonin administration in similar experiments. In liver tissue both amines caused a decrease in glycogen concentration and did not affect its content in skeletal muscles. Possible interrelationship is discussed between phosphorolysis and hydrolysis of glycogen under conditions of myocardial hypoxia, caused by noradrenaline administration.