García-Sáinz J A, Casas-González P, Romero-Avila M T, González-Espinosa C
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D. F.
Life Sci. 1994;54(25):1995-2003. doi: 10.1016/0024-3205(94)90134-1.
The alpha 1-adrenoceptors present in liver membranes from rats, hamsters and mice were characterized using [3H]prazosin. In the liver membranes from the three species a relatively large number of receptors was observed (500-900 fmol/mg of protein) and the affinities for [3H]prazosin were very similar (0.2-0.3 nM). Membrane preincubation with 10 microM chloroethylclonidine markedly decreased [3H]prazosin binding and higher concentrations essentially abolished specific binding of this radioligand. Binding competition experiments indicated the following orders of potency: a) for agonists: oxymetazoline > epinephrine > or = norepinephrine >> methoxamine and b) for antagonists: prazosin > WB 4101 > or = phentolamine = benoxathian > 5-methyl urapidil. The affinity for (+)niguldipine was also low but there was variation between the three species. Total RNA obtained from the liver of these species hybridized with the alpha 1B-adrenergic cDNA probe. The data suggest that these receptors correspond to the alpha 1B subtype.
利用[³H]哌唑嗪对大鼠、仓鼠和小鼠肝膜中的α1 -肾上腺素能受体进行了表征。在这三种动物的肝膜中观察到相对大量的受体（500 - 900 fmol/mg蛋白质），并且它们对[³H]哌唑嗪的亲和力非常相似（0.2 - 0.3 nM）。用10 μM氯乙可乐定对膜进行预孵育可显著降低[³H]哌唑嗪的结合，更高浓度则基本消除了这种放射性配体的特异性结合。结合竞争实验表明了以下效价顺序：a）对于激动剂：羟甲唑啉＞肾上腺素＞或 = 去甲肾上腺素＞＞甲氧明；b）对于拮抗剂：哌唑嗪＞WB 4101＞或 = 酚妥拉明 = 贝诺沙嗪＞5 -甲基乌拉地尔。对（+）尼群地平的亲和力也较低，但三种动物之间存在差异。从这些动物肝脏获得的总RNA与α1B -肾上腺素能cDNA探针杂交。数据表明这些受体对应于α1B亚型。
