title: Adaptive changes in the responsiveness of adenylate cyclase to catecholamines.
abstract: Exposure of the intact astrocytoma cell to isoproterenol not only causes the activation of adenylate cyclase and the accumulation of cyclic AMP but sets in motion a complicated series of events designed to down-regulate the system if exposure to the agonist is extended in time. We have identified at least three of these processes: (1) a rapid uncoupling of the beta-receptor--adenylate cyclase system with subsequent loss of beta-receptors; (2) a slower, nonspecific desensitization of adenylate cyclase to the effects of all classes of receptor agonists by a process that may be mediated by cyclic AMP; and (3) a slow induction of phosphodiesterase activity that is probably mediated by cyclic AMP.
mesh_terms: D000262:Adenylyl Cyclases / Q000096:biosynthesis / Q000378:metabolism*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000437:Alcoholism / Q000378:metabolism; D000818:Animals; D001254:Astrocytoma / Q000378:metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis / Q000378:metabolism; D004361:Drug Tolerance; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D008954:Models, Biological; D009638:Norepinephrine / Q000494:pharmacology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D051381:Rats; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000318:Adrenergic beta-Agonists; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D000431:Ethanol; D000242:Cyclic AMP; D010727:Phosphoric Diester Hydrolases; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D009638:Norepinephrine