Plasma lipid transfer activity in rabbits: effects of dietary hyperlipidemias

Studies were performed in the rabbit to investigate the relationship between plasma lipids and the cholesteryl ester/triglyceride transfer activity of lipoprotein-deficient plasma (d greater than 1.21). The time courses for diet-induced changes in plasma lipids and the lipid (cholesteryl ester/triglyceride) transfer activity of lipoprotein-deficient plasma (LTA) were determined in rabbits fed a variety of hyperlipidemic diets. LTA was not altered within 36 h after a single high-cholesterol/oil meal despite a near doubling of the concentration of plasma cholesterol. With high cholesterol and/or high-fat feeding, LTA increased and reached new steady state levels within about 10 days with little additional change for up to 87 days even when plasma cholesterol continued to increase. For all diets, the greatest increments in LTA occurred about 5 days after initiation of experimental feeding. A low-cholesterol (0.05-0.2%, w/w) diet and a cholesterol-free, high-coconut oil diet (14%, w/w) were associated with comparable increases in both plasma cholesterol and LTA. A marked, concomitant increase in plasma triglycerides was not associated with a further increase in LTA in hypercholesterolemic rabbits. These data indicate that in the rabbit LTA increases in a parabolic manner with moderate and gross, diet-induced increases in plasma cholesterol, and the time courses for the diet-induced changes in LTA are similar for a variety of hyperlipidemic diets.