Fig. 1.

ABCA1-dependent cholesterol efflux activities of apoA-I oxidized by MPO. (A) [³H]Cholesterol efflux from ABCA1-transfected BHK cells was measured after a 2-h incubation with 3 µg/ml of apoA-I, apoA-I exposed to MPO in the presence of H₂O₂ and either NaCl (MPO-Cl) or NaNO₂ (MPO-NO₂), or apoA-I exposed to reagent HOCl or ONOO⁻. Oxidation reactions were carried out at the indicated ratio (mol:mol) of oxidant to apoA-I. (B) [³H]Cholesterol efflux was measured during 2-h incubations with the indicated concentrations of control apoA-I or apoA-I treated with a 25:1 ratio (mol:mol) of oxidant to apoA-I. [³H]Cholesterol efflux is expressed as % of total medium and cell [³H]cholesterol that is released into the medium. Results are means ± SD of three determinations, and are representative of more than six independent experiments.