Postjunctional adrenergic receptors in the rabbit eye: Effects on uveal flow and intraocular pressure in isolated arterially perfused eyes

In uveal vessels of isolated arterially perfused rabbit eyes there is direct evidence for the presence of post-junctionalα1-receptors and indirect evidence forα2-receptors. Since vasoconstriction by epinephrine could not be blocked by anα1-antagonist, only 30% by anα2-antagonist and almost fully by the combination or by phentolamine, we suggest the presence of an intermediateα-type receptor which is neitherα1 norα2 but has characteristics of either. Allα-types produce vasoconstriction and a fall in IOP. Of the β-types only β1-receptors can be demonstrated. They mediate vasodilatation and a rise in IOP. Neither β2-nor non-selective β-agonists or -antagonists (e.g. timolol) affect IOP or uveal flow.