Exchange of plasma radioactive cholesterol with atheroma lipids in situ and implanted subcutaneously

Physicochemical exchange of radioactive cholesterol was investigated in mildly hypercholesterolaemic rabbits. Such exchange was examined in erythrocytes and atheroma lipids in situ in the aortic wall and in such lipids when implanted subcutaneously. The implanted atheroma lipids gained radioactivity from intravenously injected [3H]cholesterol, even though cholesterol was being resorbed from the implants. Autoradiography showed exchange between plasma cholesterol and both intracellular and dispersed extracellular lipid in these implants. Cholesterol crystals in both implants and atheromatous lesions labelled only sluggishly. The results are consistent with the view that physicochemical exchange is a major factor in cholesterol movement in vivo.