Effects of Antiglaucoma Medications on Bovine Trabecular Meshwork Cells In Vitro

Abstract

Using an in vitro culture system, we investigated the effects of five antiglaucoma drugs on growth and morphologic characteristics of bovine trabecular meshwork cells. Epinephrine hydrochloride (55-550 [mu]M) and pilocarpine hydrochloride (0[middle dot]8-16 mM), when added to the cultures for 3 days, inhibited trabecular cell growth in a dose-dependent manner. The lowest concentration at which the inhibitory effect was observed was 109 [mu]M and 0[middle dot]8 mM, respectively, for epinephrine and pilocarpine. Dipivefrin hydrochloride (26-260 [mu]M), timolol maleate (116-1160 [mu]M), and levobunolol hydrochloride (150-1500 [mu]M) were also added to the cells for 3 days. These drugs caused a reduction in cell density, respectively, at concentrations higher than 103, 460, and 616 [mu]M. Cell elongation was seen in cultures treated with epinephrine and dipivefrin, whereas levobunolol and timolol induced the cells to adopt a rounded appearance. Cells that had been exposed to pilocarpine were enlarged with numerous vacuoles.By scanning electron microscopic techniques, epinephrine, timolol, and levobunolol were found to retard the phagocytosis of latex beads by trabecular meshwork cells. Immunostaining with the use of antibodies to vimentin and actin revealed disorganization and condensation of cytoskeletal fibers in trabecular meshwork cells after treatment with epinephrine and dipivefrin. Little change was seen with comparable concentrations of a preservative, benzalkonium chloride, and a vehicle, Liquifilm tears. These results showed that antiglaucoma drugs, depending on their concentrations, may profoundly influence the growth and activity of trabecular meshwork cells.