[Effect of beta-blockers on retinal function in vitro]

In an attempt to identify possible beta-adrenergic mechanisms in the cat retina the authors extended their previous studies on the effects of beta-agonists (Graefe's Arch. clin. exp. Ophthalmol. 225: 33-38, 1987) to three beta-adrenergic antagonists: propranolol, ICI 118.551, and timolol were applied in micromolar concentrations to the arterially perfused, dark-adapted cat eye. The rod ERG b-wave was generally depressed, sometimes enhanced after initial depression (propranolol), without showing any clear-cut dose-dependency. In contrast, the rod-mediated optic nerve action potential exhibited dose-dependent depression of the plateau and OFF components. All effects were reversible within 60-80 minutes. These results, in conjunction with earlier data on the effects of beta-agonists and recent biochemical and autoradiographic studies, strongly support the theory that there are beta-adrenergic synaptic mechanisms located in the inner layers of the mammalian retina.