Tran V T
Department of Ophthalmology, University of Southern California School of Medicine, Los Angeles.
Exp Eye Res. 1992 Sep;55(3):413-7. doi: 10.1016/0014-4835(92)90113-7.
Beta-adrenergic receptors on cultured human retinal pigment epithelium were demonstrated by the binding of [125I]cyanopindolol. Its pharmacologic specificity was also examined. Specific [125I]cyanopindolol binding was saturable, with a dissociation constant of 130 pM and a receptor density of 12 fmol per one-half million cells, which is equivalent to 14,000 receptor sites per retinal pigment epithelial cell. Agonists competed for specific [125I]cyanopindolol binding, with the following rank order of potencies: (-)-isoproterenol > (-)-epinephrine > (-)-norepinephrine. Beta 2-selective antagonist ICI-118551 was approximately 3 log orders more potent than the beta 1-selective antagonist, betaxolol. These receptors were also coupled to an adenylate cyclase. These results suggest strongly that cultured human retinal pigment epithelial cells possess beta 2-adrenergic receptors. The potential significance of these findings with regard to retinal pigment epithelial functions is discussed herein.
通过[125I]氰吲哚洛尔的结合，证实了培养的人视网膜色素上皮细胞上存在β-肾上腺素能受体。还研究了其药理学特异性。特异性[125I]氰吲哚洛尔结合具有饱和性，解离常数为130 pM，每50万个细胞的受体密度为12 fmol，相当于每个视网膜色素上皮细胞有14,000个受体位点。激动剂竞争特异性[125I]氰吲哚洛尔结合，其效力顺序如下：（-）-异丙肾上腺素>（-）-肾上腺素>（-）-去甲肾上腺素。β2选择性拮抗剂ICI-118551的效力比β1选择性拮抗剂倍他洛尔强约3个对数级。这些受体也与腺苷酸环化酶偶联。这些结果强烈表明，培养的人视网膜色素上皮细胞具有β2-肾上腺素能受体。本文讨论了这些发现对视网膜色素上皮功能的潜在意义。
