FIGURE 5.

HDL cholesterol levels before versus after recombinant apoA-I injections. Plasma HDL free cholesterol (top), cholesteryl ester (middle), and total cholesterol (bottom) levels were quantified in human hLCAT^Tg/Tg, apoA-I^−/− mice before versus after subcutaneous injection of the indicated endotoxin-free recombinant apoA-I (WT versus NO₂-Tyr¹⁶⁶-apoA-I; 4 mg/animal). Serum samples were collected at the indicated time points. The LDL fraction was precipitated, and then cholesterol and cholesteryl ester content of HDL were quantified by stable isotope dilution gas chromatography with on-line mass spectrometry, as described previously (28). Data shown represent the mean ± S.D. of triplicate experiments. p values were determined by Student's t test.