Dose- and time-dependent decrease in TM mRNA levels in HUVECs treated with ox-LDL or crude lipid extracts from ox-LDL. (A-B) Cells were treated for 12 hours with or without various concentrations of ox-LDL or 200 μg protein/mL native LDL (n-LDL). (C-D) Cells were treated with 200 μg protein/mL ox-LDL for various times. (E-F) Cells were treated for 12 hours with or without crude lipids extracts (lipids) from ox-LDL or from 200 μg protein/mL n-LDL. The lipid concentrations are expressed as the equivalent concentration of phospholipids (PL) in various concentrations of ox- or n-LDL. The crude lipid extracts containing 200 μg/mL PL from LDL are of equal concentration to those in 200 μg protein/mL LDL. (G-H) Cells were treated for various times with the crude lipids containing 200 μg PL/mL extracted from ox-LDL. Total RNA was extracted from the cells, and TM mRNA levels in the cells were analyzed by quantitative RT-PCR as described in “Materials and methods.” (B,D,F,H) The autoradiograms of panels B, D, F, and H were analyzed by densitometry and the results are expressed in panels A, C, E, and G, respectively, as a percentage of control values after normalization to the β-actin mRNA signal. Panels A, C, E, and G represent the mean ± SD from 4 independent experiments, and panels B, D, F, and H show representative results.