Low density lipoprotein labelling characterizes experimentally induced atherosclerotic lesions in rabbits in vivo as to presence of foam cells and endothelial coverage.

The entry of autologous iodine-125 low density lipoprotein (125I-LDL) into the aortic wall in rabbits was measured. After abdominal endothelium abrasion with a Fogarthy catheter the animals were fed a 1% cholesterol-supplemented diet for 4 weeks. The animals were killed 1-48 h after administration of 25 muCi 125I-LDL. Local entry of radiolabelled LDL was estimated and correlated to endothelial surface lining and foam cell content, both controlled morphologically. Endothelialized segments showed the lowest entry of 125I-LDL, the maximum uptake was reached at around 8 h. In de-endothelialized segments the entry was higher and the peak later (12 h), while in re-endothelialized segments a continuous increase in 125I-LDL entry up to 48 h was measured. Number and extent of foam cells correlated with the entry of LDL. The data indicate the usefulness of LDL radiolabelling for qualitative in vivo information on surface lining and foam cell content.