title: Desensitization of beta-adrenergic stimulated adenylate cyclase in turkey erythrocytes.
abstract: Desensitization of catecholamine stimulated adenylate cyclase (AC) activity is demonstrated in membranes derived from turkey erythrocytes pre-treated with isoproterenol. Membranes from desensitized cells had a loss in maximal catecholamine stimulated adenylate cyclase activity of 104 +/- 13 (pmols/mg protein/10', p less than .001) compared with controls. When adenylate cyclase was maximally stimulated with NaF or Gpp(NH)p, the decrements were 84 +/- 19 (p less than .005) and 92 +/- 32 (p less than .05) pmol/mg protein/10' respectively. There was no change in beta-adrenergic receptor number in membranes derived from treated cells. While the molecular mechanism accounting for the desensitization is uncertain, the data is consistent with the hypothesis that there is a lesion distal to the beta-adrenergic receptor, possibly involving the nucleotide site or the catalytic subunit of adenylate cyclase, causing the desensitization in the isoproterenol treated cells.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000201:enzymology*; D004912:Erythrocytes / Q000201:enzymology*; D007545:Isoproterenol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D013268:Stimulation, Chemical; D014422:Turkeys
chemical_list: D011943:Receptors, Adrenergic, beta; D011433:Propranolol; D000262:Adenylyl Cyclases; D007545:Isoproterenol