Fig. 1.

HDL and apoAI enhance cholesterol efflux and transendothelial cholesterol transport. (A–B) MAECs grown in transwell inserts were incubated for 18 h with [³H]-cholesterol (³H-Ch) liposome solution in the basolateral compartment, and with the indicated concentrations of HDL (A) and apoAI (B) in the apical compartment. The radioactivity in the apical medium was counted for determination of basolateral-apical transcellular cholesterol transport. (C) MAECs grown in transwell inserts were incubated for 18 h with ³H-Ch liposome solution in the apical compartment, and with 50 µg/ml HDL, 20 µg/ml apoAI or control medium in the basolateral compartment. The radioactivity in the basolateral medium was counted for determination of apical-basolateral transcellular cholesterol transport. (D) MAECs grown in transwell inserts were labeled with ³H-Ch, and then incubated with 50 µg/ml HDL, 20 µg/ml apoAI or control medium in both apical and basolateral (BLA) compartments. After a 4 h incubation, the rate of cholesterol efflux into the apical or BLA medium was determined, respectively, by counting the radioactivity in these media. Values represent the mean ± SEM of 4–5 independent experiments. * P<0.05 vs. cells without HDL or apoAI treatment (control), ^† P< 0.05 vs. 50 µg/ml HDL, ^‡ P<0.05 vs. 15 µg/ml apoAI, and ^$ P< 0.05 vs. HDL or apoAI treatment in the apical compartment.