Opacification of isolated rat lenses intoxicated with diethylmaleate: relation to lens membrane dysfunction.

We examined whether opacification of rat lenses treated with diethylmaleate (DEM), a depletor of reduced glutathione (GSH), is associated with membrane dysfunction. When isolated rat lenses were incubated with 2 mM DEM for 1, 6, and 24 h, a cortical opacity appeared at 6 h and was more pronounced at 24 h. This opacification was accompanied by decreases in GSH and vitamin E (Vit. E) content and Na+,K+-ATPase activity, and an increase in water content, but not by a change in the content of thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation. Vit. E co-treatment caused a partial prevention of opacification, a complete recovery of decreased Vit. E content, attenuation of decreased Na+,K+-ATPase activity, and a decrease in TBARS content in rat lenses treated with 2 mM DEM for 24 h. Neither opacity formation nor changes in Vit. E, TBARS, and water content and Na+,K+-ATPase activity occurred in rat lenses treated for 48 h with 2 mM l-buthionine-(S,R)-sulfoximine, an inhibitor of glutathione synthesis, although a marked GSH depletion was observed. These results suggest that opacification of isolated rat lenses treated with DEM could be associated with impairment of Na+,K+-ATPase rather than GSH depletion.