Metabolism of Oxidized High Density Lipoprotein-2(ox-HDL(2)) in Rat Hepatic Sinusoidal Cells.

Incubation of rat hepatic sinusoidal cells with FITC-HDL(2), FITC-ox-HDL(2) and [(3)H]CE-HDL(2)(rHDL(2)), ox-rHDL(2) showed that binding of FITC-HDL(2) to the cells was competitive to ox-HDL(2), but not to HDL(2). The cell-endocytic fluorescence strength (FS) of FITC-HDL(2) and radioactivity of ox-rHDL(2) were 45.5% of that of FITC-HDL(2) and 61.4% of that of rHDL(2), respectively. Endocytic FS and radioactivity were mainly in TCA-precipitable and supernatant part, respectively. The cell-released FS and radioactivity were 67.7% and 10.9% of the cell-endocytic FS and the radioactivity, respectively, and both of them were mainly TCA-precipitable. These results suggest that: (1) There is probably an ox-HDL receptor on the surface of rat hepatic sinusoidal cells, which is different from HDL receptor. (2) The metabolic behaviour of ox-rHDL(2) in the cells is similar to HDL(2). Both of them do not take a lysosomal pathway. Apoproteins and CE components dissociate from endocytic lipoprotein in the cells. After the cells have taken up most of CE, the residual CE recombines with apolipoprotein to form a lipoprotein and is released from the cells by retroendocytosis. (3) Oxidative modification of HDL(2) weakens its ability to cholesterol reverse transport.