The metabolic process of breaking down storedglycogeninliverintoglucosesubunits (i.e. glucose-6-phosphate) using inorganic phosphate for use in energy metabolism
Glycogenolysis is the process of breaking down storedglycogenin the liver so that glucose may be produced for use in energy metabolism. The process makes use of an inorganic phosphate. Two key enzymes in glycogenolysis are glycogen phosphorylase and debranching enzyme. Glycogen phosphorylase catalyzes the release of glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond. Debranching enzyme lops off the branches.1
Glycogenolysis occurs in thehepatocytes. Glycogen in the liver is broken down to provide a source of blood glucose especially during in between meals when blood glucose level is low. The opposite of glycogenolysis is glycogenesis, which is the process whereinglucosemolecules are added to chains ofglycogenfor storage. Glycogenolysis andglycogenesisare regulated by the effects of hormones, glycagon and insulin.胰高血糖素stimulates glycogenolysis; insulin inhibits it and favors glycogenesis. Thus, one of the main functions of glycogenolysis is for the regulation of glucose concentration in the bloodstream, however, in the short term only (see gluconeogenesis for long term. The pancreatic alpha cells secrete glucagon in response to low blood glucose, for instance as a result of moderate exercise or fasting.
Glycogenolysis also takes place in myocytes, particularly, during the fight-or-flight response. The hormone that regulates it is epinephrine. Glucogenolysis in myocytes differ from that inhepatocytes in a way that the former generally does not lead to the release of glucose into the bloodstream but stays within the myocyte for glycolysis.
Other regulators of glycogenolysis include cortisol, human growth hormone, and intracellular enzymes.1
1Naish, J. & Court, D. S. (2014).Medical Sciences。爱思唯尔健康科学。75年p。76.