OXIDIZED LOW-DENSITY LIPOPROTEINS INDUCE APOPTOSIS IN AORTIC AND ENDOCARDIAL ENDOTHELIAL-CELLS

AIM: To examine whether oxidized low-density lipoproteins (ox-LDL) mig ht induce apoptosis in bovine aortic and endocardial endothelial cells (BAEC and BEEC). METHODS: Low-density lipoproteins (LDL) were isolate d from healthy human plasma by ultracentrifugation and oxidized by CuS O4, 10 mu mol.L-1. BAEC and BEEC were incubated in a medium containing ox-LDL, LDL, or phosphate-buffer solution (PBS) as control. DNA fragm entation was visualized by agarose gel electrophoresis and determined quantitatively using Hoechst-33258 fluorochrome. RESULTS: Ox-LDS, not LDL, elicited typical apoptotic changes and DNA fragmentation in BAEC and BEEC. In BAEC, dextran sulfate, and cicloheximide (Cic) exhibited no effect on DNA fragmentation induced by ox-LDL. Butylated hydroxytol uene (BHT) 20 mu mol.L-1 completely inhibited Cu2+-mediated oxidation of LDL as well as the apoptosis-inducing effect of Cu2+-exposed LDL. L ysophosphatidylcholine (LPC) did not elicit DNA fragmentation in BAEC and in BEEC. DNA fragmentation induced by ox-LDL in BAEC and. in BEEC was blocked by chelating the calcium of the culture medium by egtazic acid. CONCLUSION: Ox-LDL induces apoptosis in BAEC and BEEC without in volving the LPC.