REDUCED CHOLESTEROL EFFLUX TO MILDLY OXIDIZED HIGH-DENSITY-LIPOPROTEIN

Mild oxidation (<6h) of human high density lipoprotein (HDL) induced b y incubation with copper ions increased its thiobarbituric acid reacti vity, decreased its phospholipid content, increased its free cholester ol to phospholipid ratio and reduced its ability to mediate cholestero l efflux from cells. While protein modification did occur with further oxidation (>12h), diminished efflux of cell cholesterol was apparant for HDL samples without increased electrophoretic mobility or altered apolipoproteins. Thus, reduced cholesterol efflux to mildly oxidized H DL may reflect changes in its lipids rather than its apoproteins. By l imiting cholesterol removal from cells, any mild oxidation of HDL whic h might occur in vivo could contribute to cellular cholesterol accumul ation. (C) 1994 Academic Press, Inc.