On the mechanism of hepatic glycogenolysis induced by anoxia or cyanide.
Addition of glucagon to isolated hepatocytes increased glycogenolysis and phosphorylase a in a proportional manner. KCN caused slightly more glycogenolysis at considerably lower levels of phosphorylase a; the discrepancy was most pronounced after pretreatment of the hepatocytes with EGTA. When incubated with tagatose, the hepatocytes accumulated tagatose 1-phosphate, a presumed inhibitor of phosphorylase a. In these conditions the glucagon-induced glycogenolysis was blocked, but the glycogen loss caused by KCN or anoxia was not affected. Cyanide and anoxia may allow phosphorylase b and a to become equally active, or they may trigger a non-phosphorolytic glycogenolysis.
D000818:Animals; D003486:Cyanides / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology; D006601:Hexoses / Q000494:pharmacology; D000860:Hypoxia / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism*; D008297:Male; D010762:Phosphorylase a / Q000378:metabolism; D011190:Potassium Cyanide / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D003486:Cyanides; D006601:Hexoses; D008112:Liver Glycogen; D005934:Glucagon; D010762:Phosphorylase a; D011190:Potassium Cyanide; C030192:tagatose