Separation of the different classes of intrahepatic lipoproteins from various animal species. Their binding with 2,3,7,8-tetrachlorodibenzo-p-dioxin and benzo(a)pyrene.

Using several analytical methods, including sucrose density gradient and potassium bromide density gradient ultracentrifugations, we have demonstrated that liver cells contain a range of lipoproteins somewhat distinct from those found in plasma. In addition to very low-density lipoproteins (VLDL), low-density lipoproteins (LDL) and high-density lipoproteins (HDL), many heavier entities have been found in the cytosol of various animal species. These heavier entities might represent either anabolic or catabolic intermediates of lipoproteins. Labelled hydrophobic xenobiotics such as 2,3,7,8-tetrachlorodibenzo-p-dioxin or benzo(a)pyrene strongly bind to the various classes of lipoproteins and may be used as radioactive tracers in the analysis and possibly in the metabolic studies of intracellular lipoproteins. Moreover, this binding may be a prerequisite for a storage or/and a carrier--roles of lipoproteins in the intracellular distribution of lipophilic xenobiotics within the cells.