[Effect of phosphatidic acid on the radiation-initiated peroxidation of phosphatidylcholine in liposomes].

It was found that the incorporation of anionic dipalmitoyl phosphatidic acid (DPPA) into phosphatidylcholine (PC) liposomes up to 15 mol % was accompanied by the intensification of accumulation of diene conjugates (DC), which are primary products of lipid peroxidation (LPO), if the LPO was initiated by gamma-irradiation of a 137Cs source. Monoethyl ester of DPPA, phosphatidylethanol (DPPEt), exerted a lesser influence at the same concentrations. Ca2+ ions inhibited the DC production not only in liposomes consisting of lipid mixture but in lipid membranes of PC alone as well.

[Effect of lysophosphatidylcholine on the radiation-induced lipid peroxidation in liposomes].

The effect of lysophosphatidylcholine (LPC) on the lipid peroxidation process (LPO) in liposomes of rat liver phosphatidylcholine initiated by irradiation of 137Cs source was studied. The formation of diene conjugates (DC) is shown to increase dramatically on incorporation of more than 10% LPC into liposomes. The dependence of DC proportion on the irradiation dose is practically linear in the range of 0 to 5 kGy.

[The characteristics of the radiation-initiated peroxidation of the phosphatidylcholine making up liposomes containing phospholipids which are susceptible to free-radical fragmentation].

The regularities of accumulation of conjugated dienes and thiobarbituric acid (TBA)-reactive substances under gamma-irradiation of liposomes from rat liver phosphatidylcholine (PC) and its mixtures with the resistant to lipid peroxidation saturated phospholipids and bovine brain sphingomyelin (SM) were studied. It was established that the incorporation of negatively charged dipalmitoylphosphatidylglycerol (DPPG) and dipalmitoylphosphatidylethanol (DPPET) into lipid bilayer resulted in the increase of primary and secondary products of LPO, whereas neutral dipalmitoylphosphatidylcholine (DPPC) and SM involving in the phospholipid mixtures inhibited the peroxidation of PC. For anionic phospholipids, DPPG had more profound activating action on LPO, amongst the neutral phospholipids SM was more potent inhibitor of the reaction.