3342 Cholesterol may modulate membrane susceptibility to oxidation in cataractous lens

AGE RELATED LIPID OXIDATION IN HUMAN LENS MEMBRANES BY INFRARED SPECTROSCOPY. Borchman D. Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville Kentucky, 40202, USA. To measure primaty and secondary products of lipid Purnose oxidation with age in human lens membranes. Lipid oxidation is believed to contribute to a number of senescent diseases including cataract. Secondary products of lipid oxidation, such as malondialdehyde, have been measured in the lens and are not a good indicator of lipid oxidation. hence primaly and secondary products were measured in this stidy. Methods Lipids were extracted from 1 to 85 year old human lenses using a monophasic extraction protocol. Extracted lipid was dried on a AgCl window for infrared spectroscopic analysis. Infrared bands due to lipid oxidation were quantified: trans double bonds, hydroperoxides, carbonyls. These bands were compared to infrared bands representative of total lipid: the symmetric and asymmetric phosphate bends, CH stretching bands, cis double bond CH stretching band. Results Primary products of lipid oxidation increased linearly from 1 to 85 years. The ratio of trans to cis double bonds increased 7 fold during this period while all orher products increased 3 fold relative to one mole of phospholipid. Conclusions Lipid oxidation is substantial and increases linearly with age in the human lens. These products would be expected to increase membrane permeability diminish cation pump activity, crosslink proteins, destroy DNA and contribute the to the senescent related increase in membrane rigidity. A threshold of lipid oxidation could be reached upon which cataracts develop.