Localization of alpha-2 adrenergic receptors in the human eye.

To elucidate sites of the action of alpha-2 adrenergic drugs, we localized binding sites for a potent alpha-2 adrenergic agonist, UK-14,304, in sections of the human cadaveric eye by an in vitro ligand-binding technique and autoradiography. Its specific binding sites were found in the iris epithelium and ciliary epithelium at a high level, and also in the ciliary muscle, retina, retinal pigment epithelium (and/or choroid). Binding of UK-14,304 to the ocular pigments was prevented by preincubating the eye sections with chloroquine, which reduced the non-specific binding to a low level.