title: Synthesis and characterization of CGP-12177-NBD: a fluorescent beta-adrenergic receptor probe.
abstract: The synthesis and properties of a fluorescent derivative of the hydrophilic beta-adrenergic antagonist CGP-12177 are described. The fluorescence of the NBD derivative of CGP-12177 (CGP-NBD) is extremely sensitive to its environment, the quantum yield increasing 23-fold upon transfer from water to acetonitrile. This property of CGP-NBD was taken into account and a procedure was developed using quantitative chloroform extraction of ligand for the measurement of CGP-NBD bound specifically to beta-receptors on A431.E3 membranes. The fluorescent NBD-derivative of CGP-12177 bound strongly and specifically to A431 cells, a KD of 3.9 x 10(-10) M being measured; the specific binding represented 63% of the total binding at a concentration of 1 x 10(-8) M (256 x KD). A431.E3 cells were used for the binding studies since they gave consistently higher receptor numbers when compared with the native strain. A maximal number of 47,000 sites/cell and a KD of 100 pM were measured with CGP-12177 on adhered cells. The receptor number was strongly dependent upon cell density with only 3000 sites/cell being measured in suspension at confluence.
mesh_terms: D009327:4-Chloro-7-nitrobenzofurazan / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000378:metabolism*; D000319:Adrenergic beta-Antagonists; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D004910:Erythrocyte Membrane / Q000378:metabolism; D005456:Fluorescent Dyes; D007700:Kinetics; D010069:Oxadiazoles / Q000378:metabolism*; D011412:Propanolamines / Q000138:chemical synthesis / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D012997:Solvents; D013050:Spectrometry, Fluorescence; D014422:Turkeys
chemical_list: D000319:Adrenergic beta-Antagonists; D005456:Fluorescent Dyes; D010069:Oxadiazoles; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D012997:Solvents; C057209:CGP 12177-NBD; D009327:4-Chloro-7-nitrobenzofurazan; C033394:CGP 12177