Docherty J R, Starke K
J Cardiovasc Pharmacol. 1981 Jul-Aug;3(4):854-66. doi: 10.1097/00005344-198107000-00019.
Postsynaptic alpha-adrenoceptor subtypes were investigated in vitro, employing rabbit aorta, pulmonary artery, and portal vein, and rat anococcygeus. Phenylephrine (alpha 1-selective), alpha-methylnoradrenaline (mixed agonist), and xylazine (alpha 2-selective) were used as agonists, and prazosin (alpha 1-selective) and rauwolscine (alpha 2-selective) as antagonists. In all tissues, agonist concentration-response curves were monophasic and their shape was unaltered by either antagonist. In rabbit blood vessels, prazosin was as potent against alpha-methylnoradrenaline as against phenylephrine and was 1,000 times more potent than rauwolscine; xylazine was a partial agonist of low potency. Hence, the postsynaptic receptors of these tissues are alpha 1. In the rat anococcygeus, there was some evidence for an alpha 2-receptor: xylazine was a full and potent agonist, rauwolscine was more potent against xylazine than against alpha-methylnoradrenaline or phenylephrine, and in experiments protecting against irreversible blockade by phenoxybenzamine, xylazine afforded significantly greater protection to alpha-methylnoradrenaline than to phenylephrine. However, prazosin was more potent than rauwolscine against xylazine and was equipotent against all agonists. Hence, although the smooth muscle cells of the rat anococcygeus may contain alpha 2-adrenoceptors, the predominant population is alpha 1.
利用兔主动脉、肺动脉、门静脉以及大鼠的肛门尾骨肌在体外研究突触后α-肾上腺素能受体亚型。使用去氧肾上腺素（α1选择性）、α-甲基去甲肾上腺素（混合激动剂）和赛拉嗪（α2选择性）作为激动剂，哌唑嗪（α1选择性）和育亨宾（α2选择性）作为拮抗剂。在所有组织中，激动剂浓度-反应曲线均为单相，且其形状不受任何一种拮抗剂的影响。在兔血管中，哌唑嗪对α-甲基去甲肾上腺素的效力与对去氧肾上腺素的效力相同，且比对育亨宾的效力强1000倍；赛拉嗪是一种低效的部分激动剂。因此，这些组织的突触后受体为α1受体。在大鼠肛门尾骨肌中，有一些证据表明存在α2受体：赛拉嗪是一种强效的完全激动剂，育亨宾对赛拉嗪的效力比对α-甲基去甲肾上腺素或去氧肾上腺素的效力更强，并且在防止苯氧苄胺不可逆阻断的实验中，赛拉嗪对α-甲基去甲肾上腺素的保护作用比对去氧肾上腺素的保护作用明显更大。然而，哌唑嗪对赛拉嗪的效力比对育亨宾的效力更强，且对所有激动剂的效力相当。因此，尽管大鼠肛门尾骨肌的平滑肌细胞可能含有α2肾上腺素能受体，但主要群体是α1受体。
