title: Hormonal regulation of hepatic glycogenolysis in the carp, Cyprinus carpio.
abstract: Carp (Cyprinus carpio) liver maintained normal glycogen content and enzyme complement for several days in organ culture. Epinephrine-stimulated glycogenolysis, phosphorylase activation, and cyclic AMP (cAMP) accumulation in a concentration-dependent manner with EC50s of 100, 100, and 500 nM, respectively. These actions were blocked by the beta-adrenergic antagonist, propranolol, but not by the alpha-adrenergic antagonist phentolamine. Glycogenolysis and tissue cAMP were uninfluenced by 10(-6) M arginine vasotocin, arginine vasopressin, lysine vasotocin, lysine vasopressin, mesotocin, or oxytocin, but were slightly increased by 10(-5) M isotocin and slightly decreased by 10(-6) M angiotensin II. [125I]-iodocyanopindolol (ICP), a beta-adrenergic ligand, bound to isolated carp liver membranes with a KD of 83 pM. Maximum binding of 45 fmol/mg protein was at 600 pM. Propranolol, isoprenaline, epinephrine, phenylephrine, norepinephrine, and phenoxybenzamine displaced ICP with KDs of 100 nM, 2, 20, 20, 60, and 200 microM, respectively. The alpha-adrenergic antagonists, yohimbine and prazosin, showed no specific binding. These data provide evidence that catecholamines act via beta-adrenergic receptors in carp liver and that alpha-adrenergic receptors are not present. Vasoactive peptides play no significant role in regulation of carp liver glycogenolysis.
mesh_terms: D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D002347:Carps / Q000378:metabolism*; D002395:Catecholamines / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D003530:Cyprinidae / Q000378:metabolism*; D006597:Fructose-Bisphosphatase / Q000378:metabolism; D005934:Glucagon / Q000502:physiology; D005947:Glucose / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism*; D009924:Organ Culture Techniques; D006005:Phosphorylases / Q000378:metabolism; D011770:Pyruvate Kinase / Q000378:metabolism
chemical_list: D002395:Catecholamines; D008112:Liver Glycogen; D005934:Glucagon; D000242:Cyclic AMP; D006005:Phosphorylases; D000410:Alanine Transaminase; D011770:Pyruvate Kinase; D006597:Fructose-Bisphosphatase; D005947:Glucose