EFFECTS OF OXIDATIVE STRESS ON GLYCEROLIPID ACYL TURNOVER IN RAT HEPATOCYTES

Lipid peroxidation was induced in freshly isolated rat hepatocytes by incubation in the presence of Fe3+, resulting in accumulation of thiob arbituric acid reactive substances. Analysis of lipid classes revealed that the levels and fatty acid compositions of the two major phosphol ipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), rem ained unchanged but the levels of triacylglycerols (TAG) were signific antly reduced, and some of their polyunsaturated fatty acids were sele ctively lost as the result of oxidant treatment. Acyl turnover in PC a nd PE as determined by O-18 incorporation from (H2O)-O-18-containing m edia remained largely unchanged during oxidant treatment, while some i ncreased turnover of the saturated fatty acids in TAG was observed. We hypothesize that constitutive recycling of membrane phospholipids rat her than selective in situ repair eliminates peroxidized species of PC and PE. TAG could serve as an expendable fatty acid reserve, providin g a limited but very dynamic pool of polyunsaturated fatty acids for t he resynthesis of phospholipids.