EFFECT OF LIPID-PEROXIDATION ON NA+, K+-ATPASE, 5'-NUCLEOTIDASE AND CNPASE IN MOUSE-BRAIN MYELIN

In the presence of H2O2, solutions of Fe2+ were applied to brain homogenate and isolated myelin from adult SWV control mice and the shiverer dysmyelinating mutant mouse as a source of a reactive oxygen species (Fenton reaction). Under these conditions, lipid peroxidation was initiated and measured as thiobarbituric acid-reactive oxidation products (TBAR). This was accompanied by 85% inhibition of myelin-associated Na+, K+-ATPase and 25% inhibition of 5′-nucleotidase. In contrast, CNPase activity was not altered. Studies on the shiverer mutant brain revealed that in spite of hypomyelination and prevalence of premature, myelin-like membranes in the homogenate, the myelin-related enzymes reacted as normal enzymes to peroxidation. Differences in the resistance of Na+, K+-ATPase to peroxidation in the brain homogenate and myelin suggest that the myelin enzyme in extremely sensitive to reactive oxygen toxicity. © 1990.