The retinal toxicity of befunolol and other adrenergic beta-blocking agents: inhibition of phagocytic activity of cultured retinal pigment epithelial cells.

Effects of befunolol and other beta-blocking agents on the phagocytosis of cultured retinal pigment epithelial cells (RPE cells) from the chick embryo were investigated. Toxicity was evaluated as an ability of RPE cell phagocytosis of polystylene latex spheres (PS). After an incubation with beta-blockers, PS was added to the medium. The phagocytic reaction was terminated, and particle numbers in RPE cells were counted under an oil immersion microscope. Incubation with befunolol in a range of concentration of 10(-9)-10(-3) M resulted in a time- and dose-dependent inhibition of phagocytosis. Incubation with 10(-6) M befunolol inhibited phagocytic activity down to 60% of control. The same mode of action was observed in other beta-blockers. The inhibitory effect of befunolol at 10(-4) M or lower concentrations was reversible, while incubation with 10(-3) M for 24 h was irreversible.