An elevated low-density lipoprotein (LDL) in the plasma is the most recognized risk factor in the pathogenesis of atherosclerosis. On the other hand, the concentration of high density lipoprotein (HDL), is inversely correlated with atherosclerotic coronary artery disease. The transport pathways of LDL across the arterial wall has been well established. However, little is known about the transport mechanism(s) of HDL across the arterial wall. In this study, HDL was conjugated to colloidal gold for investigation of the ultrastructural aspects of binding and uptake of HDL by aortic endothelium.

High density lipoproteins were isolated from fresh rat plasma by sequential ultracentrifugation. HDL-colloidal gold conjugates were prepared according to the modified method of Kao et al. Sprague-Dawley rats were anesthetized and the vasculature was cleared of blood by perfusion with oxygenated PBS supplemented with 1 mM CaCl2 and 14 mM glucose at 37 °C through the abdominal aorta using the vena cava as an outlet.