Binding characteristics of the selective alpha 2-adrenoceptor antagonist [3H]idazoxan to rat olfactory cortex membranes.

[3H]Idazoxan binding to membranes prepared from rat olfactory cortex obeyed saturation kinetics and was to a single population of sites. Although the density of sites was dependent on the incubation medium, binding was of high affinity (KD approximately 5.5 nM) with a Hill coefficient close to unity. Competition studies with a range of adrenoceptor agonists and antagonists confirmed that [3H]idazoxan binding was to alpha 2-adrenoceptors. Neither chemical lesions with the neurotoxin kainic acid nor chronic unilateral bulbectomy significantly altered any of the [3H]idazoxan binding parameters. These findings suggest that alpha 2-adrenoceptors are not located on the lateral olfactory tract terminals or pyramidal cells of the olfactory cortex.