Characterization of unique ADTN-catecholamine binding sites in the iris root-ciliary body of rabbits.
A binding site for tritiated 2-amino-6, 7-dihydroxy-1, 2,3,4-tetrahydronaphthalene (ADTN) has been partially characterized in the rabbit iris root-ciliary body. Binding of ADTN is proportional to protein content and requires at least 60 minutes to reach equilibrium. Binding is saturable, with a Kd of 27 +/- 1 nM and a Bmax of 2.1 +/- .3 pmol/mg protein (mean +/- SEM). Dopamine competes for this site with a Ki of 100 nM and apomorphine with a Ki of 180 nM. This site is not blocked by L-timolol, phenoxybenzamine, or by several DA1 and DA2 antagonists. It appears to be a new type of catecholamine binding site, of a type not observed outside the anterior eye. It is possible that some of the effects of dopamine on intraocular pressure are mediated through this binding site.
Rohde
B H
BH
Department of Medical Pharmacology and Toxicology, Texas A & M University College of Medicine, College Station 77843.
Chiou
G C
GC
D000818:Animals; D001667:Binding, Competitive; D002395:Catecholamines / Q000378:metabolism*; D002924:Ciliary Body / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism; D018492:Dopamine Antagonists; D007498:Iris / Q000378:metabolism*; D007700:Kinetics; D009281:Naphthalenes / Q000378:metabolism*; D011817:Rabbits; D011941:Receptors, Adrenergic / Q000187:drug effects / Q000378:metabolism*; D017983:Receptors, Catecholamine; D013764:Tetrahydronaphthalenes / Q000378:metabolism*
D002395:Catecholamines; D018492:Dopamine Antagonists; D009281:Naphthalenes; D011941:Receptors, Adrenergic; D017983:Receptors, Catecholamine; D013764:Tetrahydronaphthalenes; C011639:ADTN; D004298:Dopamine