Effect of acetyl salicylic acid on cholesterol effluxes from foam cells. Monocyte-derived macrophages loaded with radio-labeled cholesterol were incubated for 24 h with RPMI containing 0, 150, 300, 600, 1200 μM ASA and 50 mg/L HDL. Intracellular and extracellular cholesterols were counted for their radioactivity by a scintillation counter. The decreases in the cellular contents of cholesterols caused by the ASA treatments at 600, 1200 μM were statistically significant (P < 0.05, ANOVA), whereas changes of those by ASA at 150, 300 μM are not significant (P > 0.05) between samples and the control. Results are expressed as mean ±S.D, of three experiments with duplicated samples. * P < 0.05,compared to control.