Distribution of phospholipid-malondialdehyde-adduct in the human lens.

The distribution of phospholipid-malondialdehyde adduct was measured in human lenses pooled by age over a range of 13 to 68 years. Lipid extracts from sections of the central core and from the equatorial region of the lens were probed for lipid adduct using laser induced fluorescence. For an excitation of 351.1/363.8 nm the fluorescence maximum occurred at 473 nm for all ages and regions of the lens. The adduct concentration was always highest in the anterior nuclear section of the central core and decreased toward the anterior and posterior surfaces. The adduct concentration was lowest in the equatorial section for all samples. The regional distribution observed suggests that the formation of lipid-malondialdehyde adduct in the lens could be influenced by the cumulative amount of UV radiation absorbed. No changes with age were observed in the concentration of the adduct in the whole lens nor in the cortical and nuclear regions suggesting the possibility of an equilibrium between the formation and degradation of the adduct.