[Effect of high-density lipoproteins on the permeability of the rabbit aorta for low-density lipoproteins].

After administration of high doses of high density lipoproteins (HDL) into control rabbits the index of aorta permeability for 125I-low density lipoproteins (LDL) was decreased by about 19%. This index was decreased by 45% if HDL was administered into animals with hypercholesterolemia. Historadiographic assays showed that presence of 125I-LDL in circulation simultaneously with the exogenous HDL caused a decrease in the vessel wall permeability for LDL both in control rabbits and, especially, in hypercholesterolemic animals. As shown in experiments with human embryonal lung fibroblasts, under conditions of mainly unspecific interaction of LDL with cells, HDL inhibited the 125I-LDL absorption by 28%. High molar excess of HDL appears to inhibit the LDL penetration via intact endothelial layer into the arterial wall due to ability of HDL to compete with LDL at the sites of low affinity on the endothelial cells surface.