Reduced apoprotein B and increased lipoprotein turnover in cholesterol-fed rabbits after partial ileal bypass

Plasma lipid and lipoprotein levels and composition of the very low-, low-, and high-density lipoproteins (VLDL, LDL, HDL) were studied in white New Zealand rabbits in the control state, 8 weeks after initiation of a 2% cholesterol-enriched diet, and sequentially for 16 weeks following a partial ileal bypass (PIB) procedure. Turnover and aortic uptake of 125I-labeled VLDL, obtained from the rabbits before and 16 weeks after PIB, were also analyzed. A significant reduction of plasma cholesterol from the postdiet levels to well below the prediet mean, despite continuation of the high cholesterol diet, followed PIB. A very early reduction of the apoprotein B percentage content in both VLDL and LDL was observed after the procedure, even when a relative cholesterol ester enrichment of these lipoproteins was still present. HDL cholesterol levels were somewhat lowered by the experimental diet and further reduced after PIB. 125I-labeled VLDL after PIB showed a reduced arterial uptake, as compared to the same lipoproteins from animals before PIB. These findings may provide an interpretation for the decreased atherogenesis after PIB.