title: Beta-adrenergic actions on cardiac cell membranes.
abstract: Adrenergic beta receptors are located on the heart cell surface membrane and can be identified directly by ligand-binding studies in intact cells. The maximal specific binding capacity of a labeled beta-adrenergic antagonist, [3H]-CGP, corresponds to about 6000 receptors per cell. Binding of adrenergic agonist results in changes in the membrane ion permeability for Ca which appears to involve an increase in the cAMP content of cardiac cells. Studies employing tracer methods and electrophysiological techniques suggest that the number of functional Ca channels in myocardium is regulated by beta-adrenergic receptors through the involvement of cAMP-mediated phosphorylation.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000319:Adrenergic beta-Antagonists / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D007473:Ion Channels / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000201:enzymology; D009469:Neuromuscular Junction / Q000187:drug effects*; D011412:Propanolamines / Q000378:metabolism; D051381:Rats; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*
chemical_list: D000319:Adrenergic beta-Antagonists; D007473:Ion Channels; D011412:Propanolamines; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D000262:Adenylyl Cyclases; C033394:CGP 12177; D002118:Calcium