title: Hormone-stimulated glycogenolysis in isolated goldfish hepatocytes.
abstract: Hepatocytes isolated from the liver of the common goldfish Carassius auratus L. with crude bacterial collagenase maintained ATP levels for at least 2 h. Glycogenolysis was maximally activated by 1 X 10(-6) M epinephrine and 5.8 X 10(-9) M glucagon. In liver cells incubated in calcium-free buffer containing 1 mM ethylene glycol-bis-(beta-aminoethylether)-N,N'-tetraacetic acid, basal glycogenolysis was enhanced by the addition of 1-4 mM calcium but the elevation of cyclic AMP and glycogenolysis due to epinephrine was unaffected by calcium. The divalent cation ionophore A23187 did not alter basal or hormone-stimulated glycogenolysis. Isoproterenol was approximately as potent as epinephrine but phenylephrine was glycogenolytic only at very high concentrations. l-Propranolol competitively inhibited the increased glycogenolysis due to catecholamines but phentolamine was ineffective as a blocking agent. Isoproterenol and epinephrine stimulated glycogenolysis at lower concentrations than those required to elevate cyclic AMP accumulation. Phenylephrine was without effect on cyclic AMP. Propranolol competitively inhibited both epinephrine- and isoproterenol-stimulated cyclic AMP accumulation, but phentolamine did not block either response. Catecholamine-stimulated glycogenolysis in goldfish liver is apparently a beta-adrenergic effect. However, low concentrations of epinephrine enhance glycogenolysis without affecting total cyclic AMP.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000494:pharmacology; D003530:Cyprinidae / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006054:Goldfish / Q000378:metabolism*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008099:Liver / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism*
chemical_list: D008112:Liver Glycogen; D000255:Adenosine Triphosphate; D005934:Glucagon; D000242:Cyclic AMP; D006152:Cyclic GMP; D005947:Glucose; D007545:Isoproterenol; D004837:Epinephrine