Figure 3.

(A) Inhibition of ABCG1 expression reduces cholesterol and phospholipid efflux from lipid-laden macrophages. Macrophages were incubated with ¹⁴C-cholesteryl ester and ³H-choline-labeled acLDL for 2 days in the presence of a selected antisense oligonucleotide directed against human ABCG1 or a scrambled oligonucleotide (control) at the indicated concentrations. Cells were subsequently deloaded in the presence of HDL₃ for 12 h. Shown is the HDL₃-mediated efflux of intracellular ¹⁴C-cholesteryl ester and ³H-choline from macrophages that were incubated in the presence of the ABCG1-specific antisense oligonucleotide. Data are indicated relative to the efflux in cells that were treated with the control antisense oligonucleotide (0 nmol, 100%) and represent two independent experiments, each measured in triplicate. The mean counts per minute in the media and cell fractions were ABCG1 specific antisense oligonucleotide: 5 nmol, medium: 34073 (chol), 99900 (pl), cells: 71178 (chol), 347829 (pl); 10 nmol, medium: 14625 (chol), 76172 (pl), cells: 42061 (chol), 350954 (pl); control oligonucleotide: 5 nmol, medium: 34342 (chol), 99264 (pl), cells: 54279 (chol), 346660 (pl), 10 nmol, medium: 26922 (chol), 106220 (pl), cells: 44708 (chol), 339588 (pl); no oligonucleotide: medium: 38196 (chol); 113005 (pl), cells: 76361 (chol); 449088 (pl). (B) Concentration-dependent suppression of ABCG1 expression in macrophages during treatment with the ABCG1-specific antisense oligonucleotide. Cells were incubated for 2 days with acLDL in the presence of the ABCG1-specific antisense (Top) or the scrambled control oligonucleotide (Middle). Note that the expression of the cholesterol responsive transporter ABCA1 is not down-regulated by the ABCG1-specific antisense oligonucleotide (Bottom).