RT Journal Article SR Electronic T1 Characterization of Alpha-2D Adrenergic Receptor Subtypes in Bovine Ocular Tissue Homogenates JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 1171 OP 1177 VO 281 IS 3 A1 David B. Bylund A1 Laurie J. Iversen A1 William J. Matulka A1 David M. Chacko YR 1997 UL http://jpet.aspetjournals.org/content/281/3/1171.abstract AB The alpha-2 adrenergic receptors are known to be present in the mammalian eye and to mediate the effects ofalpha-2 agonists used in the treatment of glaucoma. Little is known, however, regarding the relative densities of the threealpha-2 subtypes in the various tissues of the eye. We used receptor binding experiments with the radioligand [3H]RX821002 to characterize the alpha-2 adrenergic receptors in three tissues of the bovine eye, the ciliary body, retinal pigment epithelium/choriocapillaris and iris. TheK D values in the three tissues were similar (0.12–0.14 nM), and the B maxvalues ranged from 100 fmol/mg of protein for the ciliary body and retinal pigment epithelium/choriocapillaris to 200 fmol/mg of protein for the iris. The pharmacological characteristics of thealpha-2 receptors in all three tissues of the bovine eye, as assessed by competition studies, were essentially identical and were similar to the characteristics of the alpha-2A/D receptors of the bovine neurosensory retina. The correlation coefficients between the logarithms of theK i values for the three tissues and the neurosensory retina for nine adrenergic agents were .98 to .99. We conclude that the alpha-2 adrenergic receptors in the ciliary body, iris and retinal pigment epithelium/choriocapillaris of the bovine eye are mainly alpha-2D. The American Society for Pharmacology and Experimental Therapeutics