title: Human retinal pigment epithelial cells possess beta 2-adrenergic receptors.
abstract: 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.
authors.affiliation: Department of Ophthalmology, University of Southern California School of Medicine, Los Angeles.
authors.forename: V T
authors.initials: VT
authors.lastname: Tran
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D015784:Betaxolol / Q000494:pharmacology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010857:Pigment Epithelium of Eye / Q000737:chemistry* / Q000378:metabolism; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011412:Propanolamines / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000032:analysis*
chemical_list: D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; C026777:ICI 118551; C047975:cyanopindolol; D010869:Pindolol; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D015784:Betaxolol; D009638:Norepinephrine; D004837:Epinephrine