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Aim: To examine whether oxidized low-density lipoproteins (ox-LDL) might induce apoptosis in bovine aortic and endocardial endothelial cells (BAEC and BEEC)., Methods: Low-density lipoproteins (LDL) were isolated from healthy human plasma by ultracentrifugation and oxidized by CuSO4 10 mumol.L-1. BAEC and BEEC were incubated in a medium containing ox-LDL, LDL, or phosphate-buffer solution (PBS) as control. DNA fragmentation was visualized by agarose gel electrophoresis and determined quantitatively using Hoechst-33258 fluorochrome., Results: Ox-LDL, 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 hydroxytoluene (BHT) 20 mumol.L-1 completely inhibited Cu(2+)-mediated oxidation of LDL as well as the apoptosis-inducing effect of Cu(2+)-exposed LDL. Lysophosphatidylcholine (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 involving the LPC.

Aim: To study whether estrogen might induce apoptosis in mouse peritoneal macrophages (MPM)., Method: The MPM were isolated and incubated in culture medium containing 17-beta-estradiol, estrone, or equal volume of 100% ethanol as control. DNA fragmentation was visualized by agarose gel electrophoresis., Results: 17-beta-Estradiol 0.01-1 mumol.L-1 or estrone 10-20 mumol.L-1 elicited typical morphological apoptosis and DNA fragmentation in a concentration-dependent manner in MPM. Staurosporine (Sta) 0.01 mumol.L-1, cycloheximide (Cyc) 1 mg.L-1, and tamoxifen (Tam) 10 mumol.L-1 inhibited the DNA fragmentation induced by 17-beta-estradiol 1 mumol.L-1 or estrone 20 mumol.L-1., Conclusion: Estradiol and estrone induced apoptosis in MPM.

Aim: To study the effects of oxidized low-density lipoproteins (ox-LDL) on the adhesiveness of monocytes to endothelial cells., Methods: LDL was obtained from healthy human plasma by ultracentrifugation, and oxidized by CuSO4 10 mumol.L-1. The assay of adhesion was performed using cultured bovine aortic endothelial cells (BAEC) and human peripheral blood monocytes., Results: Pretreatment BAEC with ox-LDL enhanced monocyte adhesion to BAEC in time- and dose-dependent manner. ox-LDL as little as 10 mg.L-1 and 30 min of preincubation stimulated monocyte adhesion. Cycloheximide (Cyc, a protein synthesis inhibitor) 1 mg.L-1 and staurosporine (Sta, a PKC inhibitor) 20 nmol.L-1 abolished the effect of ox-LDL (60 mg.L-1), but dextran sulfate 20 mg.L-1 had no effect on monocyte adhesion. Phorbol 12-myristate 13-acetate (PMA) 1 nmol.L-1 and lysophosphatidylcholine (Lys) 6 mumol.L-1 mimicked the effects of ox-LDL and potentiated monocyte adhesion. Sta also suppressed the augmentative effects of Lys and PMA., Conclusion: ox-LDL enhances the adhesion of monocytes to BAEC through the activation of PKC.

Aim: To examine whether oxidized low density lipoproteins (ox-LDL) might induce apoptosis in mouse peritoneal macrophages (MPM)., Methods: Low density lipoproteins (LDL) were isolated from healthy human plasma by ultracentrifugation and oxidized by CuSO4 10 mumol.L-1. MPM were incubated in a medium containing ox-LDL, LDL, or phosphate-buffer solution (PBS) as control. DNA fragmentation was visualized by agarose gel electrophoresis and determined quantitatively using Hoechst 33,258 fluorochrome., Results: Ox-LDL, not LDL, elicited typical apoptotic morphological changes (shrinkage of cytoplasm and condensation of chromatin) and DNA fragmentation in a time- and dose-dependent manner. Incubation for 24 h was necessary for ox-LDL 200 mg protein.L-1 to induce DNA fragmentation, and the maximal effect reached at 72 h. The DNA fragmentation after 24 h incubation with ox-LDL at concentrations of 100, 200, and 400 mg protein.L-1 amounted to 6.0% (P > 0.05), 9.3% (P < 0.05), and 30.9% (P < 0.01), respectively vs PBS control. Dextran sulfate, a scavenger receptor blocker and cycloheximide, a protein synthesis inhibitor, exhibited no effect on DNA fragmentation. However, antioxidant butylated hydroxytoluene (BHT) 20 mumol.L-1 completely inhibited Cu(2+)-mediated oxidation of LDL as well as the apoptosis-inducing effect of Cu(2+)-exposed LDL. Lysophosphatidylcholine (LPC), an active component in ox-LDL, at concentration up to 60 mumol.L-1, did not elicit DNA fragmentation in MPM., Conclusion: Ox-LDL induces apoptosis in MPM without involving LPC.