Different alpha 2-adrenoceptor densities in the circular and longitudinal layers of human near-term myometrium as revealed by [3H]-idazoxan binding studies.
[3H]-idazoxan, a specific alpha 2-adrenoceptor antagonist radioligand, has been used to characterize alpha 2-adrenoceptors in both circular and longitudinal layers of human near-term myometrium. [3H]-idazoxan binding is reversible, saturable and stereospecific. It labels with high affinity a single population of sites. Competition curves with different alpha 2-adrenoceptor agonists and antagonists show that the binding sites labelled with [3H]-idazoxan have the pharmacological characteristics of alpha 2-adrenoceptors. Though the KD value is similar in both layers (approximately 7 nM), the density of alpha 2-adrenoceptors in the circular layer (324 +/- 21 fmol/mg of protein) is significantly higher than in the longitudinal one (183 +/- 48 fmol/mg of protein).
D000316:Adrenergic alpha-Agonists / Q000378:metabolism; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism; D001667:Binding, Competitive; D004146:Dioxanes / Q000378:metabolism*; D004147:Dioxins / Q000378:metabolism*; D005260:Female; D006801:Humans; D019329:Idazoxan; D007700:Kinetics; D009215:Myometrium / Q000033:anatomy & histology / Q000378:metabolism*; D011247:Pregnancy / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D014316:Tritium
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D004147:Dioxins; D011942:Receptors, Adrenergic, alpha; D014316:Tritium; D019329:Idazoxan