Beta-adrenergic receptors in human anterior optic nerve: an autoradiographic study

Sections of human anterior optic nerve and nerve head were incubated in a physiological solution containing a radiolabelled beta blocker at a low concentration. The beta blocker used was (-)-(125iodo)-cyanopindolol, which has a high affinity and specificity for beta-adrenergic receptors. Concurrent incubations were performed with a great excess of unlabelled beta blocker added to demonstrate non-specific binding. Following incubation the sections were washed and dried. They were then apposed to photographic film for 5 days and developed. Incubations were performed with the stereoisomers of propranolol and an alpha blocker as well as specific beta-one and beta-two blockers. Beta-adrenergic receptors were demonstrated in anterior optic nerve and optic nerve head. The majority were of the beta-two subtype.