Effects of high-density lipoprotein on the cholesterol efflux from endothelial cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the effects of high-density lipoprotein (HDL) and oxidized high-density lipoprotein (ox-HDL) on the expression of ATP-binding cassette transporter A1 (ABCAl) and cholesterol efflux in human umbilical vein endothelial cells (HUVECs).</p><p><b>METHODS</b>In vitro cultured HUVECs were incubated in the presence of 100 microg/ml HDL or 100 microg/ml ox-HDL for 24 h, using PBS as the negative control. ABCA1 mRNA level and cholesterol efflux rate were determined using RT-PCR and a liquid scintillator, respectively.</p><p><b>RESULTS</b>HDL and ox-HDL significantly elevated the level of ABCA1 mRNA by 58% and 23% relative to the control level, respectively (P<0.05). The cholesterol efflux rate in ox-HDL group was significantly lower than that in HDL group (P<0.01).</p><p><b>CONCLUSION</b>HDL increases ABCAl expression and cholesterol efflux in HUVECs. Oxidative modification of HDL decrease cholesterol efflux by inhibiting the expression of ABCAl, suggesting a possible mechanism of ox-HDL in the pathogenesis of atherosclerosis.</p>

Effects of simvastatin on DNA synthesis in rat cardiac fibroblasts / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of simvastatin (Sim) and the interference by mevalonate (MVA) against its effect on DNA synthesis in rat cardiac fibroblasts (CFs).</p><p><b>METHODS</b>CFs were isolated from neonatal SD rats by trypsin digestion and growth-arrested CFs were stimulated with Sim and/or MVA at varied concentrations for different time lengths, and the DNA synthesis in the cells was measured by (3)H-thymidine ((3)H-TdR) incorporation assay.</p><p><b>RESULTS</b>Sim decreased (3)H-TdR incorporation in the CFs in a concentration-dependent manner, and (3)H-TdR incorporation was significantly lower in cells treated with 1 x 10(-6) and 1 x 10(-5) mol/L Sim (1,175+/-202.66 and 771+/-164.86 cpm/2000 cells, respectively) than in the control cells (1,608+/-204.32 cpm/2000 cells, P<0.01). As the treatment time with 1 x 10(-5) mol/L Sim prolonged (for 6, 12, 18, 24, 36, 42, and 48 h), (3)H-TdR incorporation in CFs decreased gradually, showing an obvious inverse correlation with the treatment time (r=-919, P<0.01). (3)H-TdR incorporation in cells treated with 1 x 10(-6) to 1 x 10(-3) mol/L MVA and 1 x 10(-5) mol/L Sim rose steadily as MVA concentration increased. A significant difference in the incorporation was found between cells treated with both 1 x 10(-4)/1 x 10(-3) mol/L MVA and 1 x 10(-5) mol/L Sim (1,612+/-308.57 and 1,995+/-353.83 cpm/2000 cells, respectively) and the cells with 1 x 10(-5) mol/L Sim treatment alone (P<0.01); difference was also noted between cells treated with 1 x 10(-5) mol/L MVA and the control cells (P<0.05), but treatment with 1 x 10(-6) mol/L MVA did not produce much difference in comparison with the control cells (P>0.05) With the increase of treatment time (for 6, 12, 18, 24, 36, 42, 48 h), 1 x 10(-3) mol/L MVA caused steady increase in (3)H-TdR incorporation in the CFs, showing a significant positive correlation with the treatment time (r=0.968, P<0.01).</p><p><b>CONCLUSION</b>Sim can decrease DNA synthesis in rat CFs and postpone the occurrence of myocardial fibrosis, which can be reversed by MVA.</p>