title: Radiation inactivation of alpha 1-adrenoceptors.
abstract: Radiation inactivation of alpha 1-adrenoceptors in rat cerebral cortex membranes has been performed with 10 MeV electrons from a linear accelerator at temperatures less than or equal to -100 degrees C. Alpha 1-adrenoceptor inactivation was monitored with [ 3H ]-prazosin and [( 125I ]-2-(beta-4-hydroxylphenyl)ethylaminomethyl)tetralone [( 125I ]-HEAT). Saturation analysis of irradiated membranes with both ligands indicated that a decrease in alpha-adrenoceptor density occurred with increasing radiation dose. The dissociation constants of [ 3H ]-prazosin and [ 125I ]-HEAT were not markedly changed by the irradiation. Application of the target volume theory gave molecular weights of 91,500 +/- 1,700 (S.D.) (D37: 19,6 +/- 0.36 Mrad) with [ 125I ]-HEAT as ligand, and 77,000 +/- 18,000 (S.D.) (D37: 23.3 +/- 4.6 Mrad) with [ 3H ]-prazosin, respectively, when an empirical temperature correction factor of 2.8 was used. [ 3H ]-flunitrazepam-labelled benzodiazepine receptor target size was used as an internal control. The molecular weight of the alpha 1-adrenoceptors, corrected for this internal control, was 85,000 +/- 1.600 [( 125I ]-HEAT) and 71,500 +/- 17,000 [( 3H ]-prazosin).
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism / Q000528:radiation effects; D005445:Flunitrazepam / Q000378:metabolism; D010627:Phenethylamines / Q000378:metabolism; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011941:Receptors, Adrenergic / Q000528:radiation effects*; D011942:Receptors, Adrenergic, alpha / Q000528:radiation effects*; D044024:Tetralones; D014316:Tritium
chemical_list: D010627:Phenethylamines; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D044024:Tetralones; D014316:Tritium; C010652:BE 2254; D005445:Flunitrazepam; D011224:Prazosin