Martire M, Pistritto G, Preziosi P
Department of Pharmacology, School of Medicine, Catholic University of the Sacred Heart, Rome, Italy.
Neurosci Lett. 1988 Apr 12;86(3):328-33. doi: 10.1016/0304-3940(88)90505-8.
The alpha 2-adrenoceptor blocking properties of idazoxan enantiomers were evaluated at pre- and postsynaptic level. The antagonism of the two idazoxan stereoisomers was assessed, at presynaptic level, by their ability to antagonize clonidine at the alpha 2-adrenoceptors regulating noradrenaline release. The antagonist (+)-idazoxan showed an affinity towards the alpha 2-autoreceptors 40 times higher than that showed by (-)-idazoxan. Binding studies revealed (+)-idazoxan to be 7-8 times more potent than (-)-idazoxan in inhibiting the p-[3H]aminoclonidine binding. These results indicate a different affinity of alpha 2-adrenoceptors for the two idazoxan stereoisomers, thus suggesting that the alpha 2-adrenoceptors located pre- and postsynaptically may be of two stereochemically different subtypes.
在突触前和突触后水平评估了咪唑克生对映体的α2 -肾上腺素能受体阻断特性。在突触前水平，通过两种咪唑克生立体异构体拮抗可乐定对调节去甲肾上腺素释放的α2 -肾上腺素能受体的能力来评估其拮抗作用。拮抗剂（+）-咪唑克生对α2 -自身受体的亲和力比（-）-咪唑克生高40倍。结合研究表明，（+）-咪唑克生在抑制p - [3H]氨基可乐定结合方面比（-）-咪唑克生强7 - 8倍。这些结果表明α2 -肾上腺素能受体对两种咪唑克生立体异构体具有不同的亲和力，因此提示位于突触前和突触后的α2 -肾上腺素能受体可能是两种立体化学不同的亚型。
