Clearance of artificial triacylglycerol particles.

In this review we discuss the metabolism of parenteral emulsions in relation to their natural counterpart, the chylomicrons. A major reaction is lipoprotein lipase-mediated hydrolysis of triglycerides at the vascular endothelium in extrahepatic tissues. The lipase is retained at the cell surface by interactions with heparan sulfate proteoglycans but can move along the surface. Lipoproteins and emulsion particles are initially steered to the endothelium by electrostatic forces. These weak interactions are reinforced by recruitment of lipase molecules. Small particles, whether injected as such or formed as remnants of larger particles, are catabolized mainly through receptor-mediated endocytosis in the liver. In contrast, many of the larger particles are removed by other, less well defined, mechanisms.