AGE-RELATED-CHANGES IN TISSUE CONTENT OF MALONDIALDEHYDE-MODIFIED PROTEINS

One of the possible mechanisms of the age-related modifications of pro teins is the result of reaction with malondialdehyde (MDA), a lipid pe roxidation byproduct. To determine the effect of age on the extent of MDA derivatization of proteins in plasma and various tissues, male Fis her 344 rats at 4, 12 and 26 months of age were studied. Protein elect rophoresis and immunoblotting was carried out using a specific antiser um against MDA-protein complexes. The concentration of MDA-proteins in plasma (mean +/- SD of optical density in 50 pg protein) was 201.6 +/ - 47.7 in 4 month old rats, 197.4 +/- 67 in 12 month old rats and 101. 4 +/- 22.7 in 26 month old rats (P<0.01). The MDA protein content of t esticle, liver and heart was increased in 12 month old rats compared t o 4 and 26 month old rats. There were no age-related differences in MD A-protein content of lung, brain, and kidney. Because of the interindi vidual variability of MDA-protein profiles within an age group distinc t age-related changes in the distribution of various MDA protein bands could not be documented.