Beta 1 and beta 2 adrenergic binding sites in bovine retina and retinal blood vessels

To supplement previous demonstration of angiotensin II and alpha-adrenergic binding sites, beta-adrenergic binding sites for dihydroalprenolol were demonstrated in vessel-free bovine neural retina (Kd = 2.5 nM) and bovine retinal vessels (Kd = 2.8 nM). By means of competition of 3H-dihydroalprenolol with betaxolol and ICI 118,551, approximately equal proportions of Beta 1 and Beta 2 subtypes were found in both the retinal vessels and the neural retina. Further studies are needed to determine the microanatomic location of the binding sites and the physiologic responses, if any, they mediate.