Effect of pretreatment of germanium-132 on Na(+)-K(+)-ATPase and galactose cataracts.
PURPOSE: Recently, we reported that topical administration of 2-carboxyethyl germanium sesquioxide (Ge-132) concurrently with 50% galactose feeding delayed the establishment of mature cataracts and reduced advance glycation product. This study was to determine the effect of pretreatment of Ge-132 on galactose associated morphological changes and Na(+)-K(+)-ATPase activity. METHODS: Young Sprague Dawley rats received topical eye drops four times a day of either saline or Ge-132 seven days prior to the 50% galactose diet and during galactose feeding. At desired intervals the lenses were extracted, photographed and processed for either light microscopy, scanning electron microscopy or the determination of Na(+)-K(+)-ATPase activity. RESULTS: In Ge-132 pretreated lenses as compared to saline pretreated lenses the following results were observed: (a) the galactose-induced morphological alterations in the majority of lenses were delayed and (b) Na(+)-K(+)-ATPase activity was protected. CONCLUSIONS: Our previous and current studies show that in addition to osmotic stress post-translational protein modification, such as glycation, including enzymes may play a role in initiating changes that lead to cataract development. The inhibition of protein glycation by antiglycating compounds, such as Ge-132, delays sugar cataract formation. Currently, we are investigating the status of protein glycation and advanced glycation end products following pretreatment with Ge-132 and the role of Ge-132 on the activities of enzymes such as aldose reductase and Na(+)-K(+)-ATPase.