Tissue-specific distribution of malondialdehyde modified proteins in diabetes mellitus.

A potential mechanism of diabetes-related tissue damage is modification of various proteins by lipid peroxidation by-products such as malondialdehyde (MDA). To determine the extent of MDA derivatization of various proteins in diabetes mellitus, Western blots were carried out using a specific anti-MDA antiserum to study proteins in plasma and various tissues of control and streptozotocin (STZ)-induced diabetic rats. The concentration of MDA-proteins was highest in plasma compared to other tissues tested. Diabetes was associated with a reduction in MDA-protein content of plasma, lung and liver while in the heart, testicle, cerebrum and kidney the MDA-protein concentration was not altered. Insulin treatment of diabetic rats normalized MDA-protein content of plasma but not in the lung or liver. A large interindividual variability in various protein species was observed within a group. This was partly attributed to polymerization of MDA-proteins. It is concluded that although diabetes is associated with increased lipid peroxidation the content of MDA-proteins in plasma and in some tissues is decreased.