title: Studies on isoproterenol stimulation of adenyl cyclase in membrane preparations from the bovine thyroid.
abstract: Catecholamine stimulation of adenyl cyclase activity associated with bovine subcellular fractions enriched in plasma membranes is described. The relative potencies of isoproterenol (IPNA), epinephrine (E), and norepinephrine (NE) were 4.7:1.0:0.02, which is characteristic for a beta-adrenergic receptor system. Stimulation with IPNA (5 times 10- minus 6 M) was inhibited by propranolol. The inhibition was stereospecific for the L-isomer of propranolol and a concentration as low as 2 times 10- minus 8 M was required to effect 50% inhibition. Both these observations, and the competitive kinetics of inhibition which applied to the system, confirmed the classification of a beta-adrenergic receptor system. Phentolamine, an alpha-antagonist, also inhibited IPNA stimulation, although high doses (5 times 10- minus M) were required to cause total inhibition. Inhibition was also observed with quinidine (1 mM) and lignocaine (10- minus 2 M).
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D004837:Epinephrine / Q000494:pharmacology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D008012:Lidocaine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011802:Quinidine / Q000494:pharmacology; D013961:Thyroid Gland / Q000201:enzymology*; D013997:Time Factors
chemical_list: D008012:Lidocaine; D011433:Propranolol; D000262:Adenylyl Cyclases; D011802:Quinidine; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine; D010646:Phentolamine