title: Para-azidoclonidine: a novel photoaffinity ligand for the alpha 2-receptor.
abstract: Reversible and irreversible interactions of the photoreactive clonidine analogue p-azidoclonidine (PAZC) with brain alpha 2-adrenergic receptors were examined. In the absence of light, PAZC displayed selective, high affinity, competitive interactions with sites labeled by the alpha 2-agonist 3H-p-aminoclonidine (3H-PAC). Reversible binding characteristics resembled those of other alpha 2-agonists. Preincubation of bovine frontal cortex membranes with 100 nM PAZC followed by ultraviolet irradiation and thorough washing decreased alpha 2-receptor density 42% relative to controls receiving irradiation alone. The loss of receptors could be prevented by inclusion of 500 nM phentolamine in the preincubation medium. Alpha 1- and beta-adrenergic receptors were relatively unaffected. PAZC is a potential photoaffinity ligand for the alpha 2-adrenergic receptor.
mesh_terms: D000345:Affinity Labels / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D003000:Clonidine / Q000031:analogs & derivatives* / Q000378:metabolism; D003624:Darkness; D007700:Kinetics; D010777:Photochemistry; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism* / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D000345:Affinity Labels; D011942:Receptors, Adrenergic, alpha; C047734:4-azidoclonidine; D003000:Clonidine