Age-related changes in tissue content of malondialdehyde-modified proteins.

One of the possible mechanisms of the age-related modifications of proteins is the result of reaction with malondialdehyde (MDA), a lipid peroxidation byproduct. To determine the effect of age on the extent of MDA derivatization of proteins in plasma and various tissues, male Fisher 344 rats at 4, 12 and 26 months of age were studied. Protein electrophoresis and immunoblotting was carried out using a specific antiserum against MDA-protein complexes. The concentration of MDA-proteins in plasma (mean +/- SD of optical density in 50 micrograms 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 testicle, liver and heart was increased in 12 month old rats compared to 4 and 26 months old rats. There were no age-related differences in MDA-protein content of lung, brain, and kidney. Because of the interindividual variability of MDA-protein profiles within an age group distinct age-related changes in the distribution of various MDA protein bands could not be documented.