HYPOCHLORITE INDUCES LIPID-PEROXIDATION IN BLOOD LIPOPROTEINS AND PHOSPHOLIPID LIPOSOMES

The accumulation of lipid peroxidation products reacting with 2-thioba rbituric acid (TBARS) has been observed both in very low density blood lipoprotein (VLDL) and suspensions of liposomes prepared from VLDL ph ospholipids incubated with hypochlorite. Butylated hydroxytoluene (EHT ) completely inhibited TBARS formation at a concentration of 100 mu M, at which it decreased the concentration of hypochlorite in the absenc e of liposomes only by 7%. The formation of lipid peroxidation product s in course of the incubation of egg yolk phospholipid liposomes with hypochlorite has been revealed using three methods: (1) measurement of TBARS, (2) measurement of additional amounts of TBARS resulting from the introduction of excess Fe2+ to peroxidized liposomes (Delta TBARS) , and (3) measurement of the chemiluminescence flash amplitude appeare d upon the addition of Fe2+ to the suspension. The results obtained by all these methods were similar: Lipid peroxidation products were accu mulated during the first 2 to 3 h of liposome incubation with 100 mu M hypochlorite, and the amount of lipid peroxidation products accumulat ed after incubation was directly proportional to the initial hypochlor ite concentration. These data suggest that hypochlorite can initiate l ipid peroxidation both in lipoproteins and phospholipid liposomes.