EFFECT OF HYDROXYL RADICAL ON NA+-K+-ATPASE ACTIVITY OF THE BRAIN MICROSOMAL-MEMBRANES

Sphingomyelin liposomes and brain microsomes were oxidized by exposure to hydrogen peroxide and ferrous ion. Lipid peroxidation were measured by the formation of thiobarbituric acid- reactive substances (TBAR). Hydroxyl radical was detected using the spin- trapping technique. Incubation of sphingomyelin liposomes with H2O2-Fe2+ resulted in an increase in the formation of TBAR. Na+-K+-ATPase activity was markedly inhibited and the SH group content decreased during incubation of microsomes in the presence of H2O2-Fe2+. Sodium ferulate effectively inhibited TBAR formation, protected Na+-K+-ATPase activity and prevented the oxidative modification of SH groups. Spin-trapping experiments showed that sodium ferulate effectively scavenged the hydroxyl radicals. © 1992 Academic Press Ltd.