Removal of double-labelled lipid mixtures and doublelabelled lipoprotein preparations by reticulo-endothelial cells

Abstract

Double-labelled lipid mixtures or double-labelled lipoprotein preparations were injected intraperitoneally into rats. Their uptake by reticulo-endothelial cells in the sternal lymph nodes was studied and the removal of the different lipids in the preparations was compared. Where a mixture of 3 H-labelled cholesterol suspension and 14 C-labelled triglyceride emulsion was taken up, the triglyceride was shown to be removed more rapidly from the reticulo-endothelial cells than was the cholesterol. Where a mixture of phospholipid suspension and cholesterol suspension was taken up the 32 P-labelled phospholipid was also removed from the reticulo-endothelial cells more rapidly than was the 14 C- labelled cholesterol. Following the uptake by reticulo-endothelial cells of serum containing β -lipoprotein labelled with 14 C (or 3 H)-labelled cholesterol and 32 P-labelled phospholipid, it was shown that the phospholipid of the lipoprotein was removed from the reticulo-endothelial cells more rapidly than was the cholesterol of the lipoprotein. The significance of these findings in relation to removal of lipid and lipoprotein taken up by the reticulo-endothelial cells in the arterial wall in atherosclerosis is discussed.