Background: Inhibition of the Na,K-ATPase by ouabain results in decreased intraocular pressure (IOP), by mechanisms that are not completely understood. Cellular mechanisms that regulate aqueous humor outflow through the trabecular meshwork (TM) include changes in TM cytoskeleton. Because inhibition of the Na,K-ATPase by ouabain alters the cell’s cytoskeleton we investigated the role of the ouabain in regulating aqueous humor outflow and TM cytoskeleton.
Method: Porcine anterior eye segment and low passage porcine TM cells were used. Outflow facility was measured using perfused anterior eye segment organ culture. Changes in TM cytoskeleton were assessed by rhodamine-phalloidin and anti-paxillin antibody staining and imaged with confocal microscopy.
Results: Ouabain (30 nM – 300 µM) increased outflow facility in perfused eye anterior segments. The time course for ouabain-induced changes in outflow facility correlated with morphological changes in the cytoskeleton of TM cells exposed to ouabain (30 nM – 300 µM). Morphological changes in TM cells include changes in actin filaments and focal adhesions.
Conclusions: These data suggest that ouabain, at non-toxic concentrations, increases aqueous humor outflow facility possibly by altering TM cell cytoskeleton.