Adrenergic influence on iris stromal pigmentation: evidence for alpha-adrenergic receptors.

Adrenergic influence on iris pigmentation in newborn pigmented rabbits was studied. Selective adrenergic antagonists were used topically to determine whether they could inhibit iris pigmentation. Unilateral, topical administration of an alpha-adrenergic antagonist (thymoxamine hydrochloride 1/2%) was not associated with iris hypochromia. Adrenergic influence on iris stromal melanogenesis appears to be mediated by alpha-adrenergic receptors.