Selective Inhibition of Membrane Atpases by Hydrogen Peroxide in the Lens of the Eye
Part of the
Basic Life Sciences
book series (BLSC, volume 49)
Oxidative damage to the lens resulting in decreased Ca-ATPase activity may play a significant role in the formation of cataracts. Deterioration of membrane function is implicated in 70% of all human lens cataracts since the intracellular calcium and sodium content of these lenses are dramatically elevated.1 Since oxidative damage to ion transport mechanisms might contribute to cataract formation,2 we chose to study the effect of hydrogen peroxide on Na-K-ATPase and Ca-ATPase activity. In fact, significant concentrations of hydrogen peroxide has been reported in the vicinity of the lens in both the human and rabbit eye in vivo. We prepared a membrane-enriched sample from Lens epithelium, cortex, and nucleus. The preparation is the same as that used routinely for preparing cardiac membranes enriched with Ca-ATPase.3 This procedure was used because commonly used lens membrane preparations utilize chaotropic agents to solubilize cytosolic lens crystallins. These chaotropic agents abolish Ca-ATPase activity. Gel electrophoresis, lipid and protein quantitation, and ATPase activity show that our preparation is enriched with plasma membranes. The lipid:protein ratio was increased 22- and 23- fold in our final cortical and nuclear membrane preparations, respectively. Total phospholipid recovery was 98.6%.
KeywordsATPase Activity Cataract Formation Lens Epithelium Minute Exposure Cataractous Lens
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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© Plenum Press, New York 1988