Torres-Márquez M E, Romero-Avila M T, González-Espinosa C, García-Sáinz J A
Departamento de Bioenergética, Universidad Nacional Autónoma de México, D.F.
Mol Pharmacol. 1992 Sep;42(3):403-6.
In isolated rat white adipocytes, epinephrine (in the presence of 10 microM propranolol) increased the uptake of [32P]Pi into phosphatidylinositol in a dose-dependent fashion. When the cells were pretreated with the irreversible antagonist chlorethylclonidine, this alpha 1-adrenergic effect was markedly diminished. The effect of epinephrine was dose-dependently antagonized by selective alpha 1-adrenergic antagonists, with the potency order prazosin greater than 5-methylurapidil greater than or equal to WB4101. Binding studies using crude membrane preparations were performed with the ligands [3H]bunazosin and 125I-HEAT. Both ligands bound to membrane sites with high affinity (Kd values of 0.75 +/- 0.20 nM for [3H]bunazosin and 125 +/- 20 pM for 125I-HEAT), in a rapid, reversible, and saturable (Bmax, 9-12 fmol/mg of protein) fashion, and with the expected pharmacological characteristics for alpha 1-adrenoceptors. Binding displacement studies with these ligands indicated a potency order of prazosin greater than 5-methylurapidil greater than or equal to WB4101. Northern blot analysis using receptor subtype-specific gene probes showed that adipocyte mRNA hybridized with the alpha 1B-adrenergic probe. All these data suggest that the alpha 1-adrenoceptors of rat white adipocytes belong to the alpha 1B subtype.
在分离的大鼠白色脂肪细胞中，肾上腺素（在存在10微摩尔普萘洛尔的情况下）以剂量依赖的方式增加了[32P]磷酸肌醇对磷脂酰肌醇的摄取。当细胞用不可逆拮抗剂氯乙可乐定预处理时，这种α1-肾上腺素能效应明显减弱。肾上腺素的作用被选择性α1-肾上腺素能拮抗剂剂量依赖性地拮抗，其效力顺序为哌唑嗪大于5-甲基乌拉地尔大于或等于WB4101。使用粗制膜制剂进行的结合研究使用配体[3H]布那唑嗪和125I-HEAT。两种配体都以快速、可逆和饱和（Bmax，9-12飞摩尔/毫克蛋白质）的方式与膜位点高亲和力结合（[3H]布那唑嗪的Kd值为0.75±0.20纳摩尔，125I-HEAT的Kd值为125±20皮摩尔），并具有α1-肾上腺素能受体预期的药理学特征。用这些配体进行的结合置换研究表明，哌唑嗪大于5-甲基乌拉地尔大于或等于WB4101的效力顺序。使用受体亚型特异性基因探针的Northern印迹分析表明，脂肪细胞mRNA与α1B-肾上腺素能探针杂交。所有这些数据表明，大鼠白色脂肪细胞的α1-肾上腺素能受体属于α1B亚型。
