ABSTRACT
Most studies dealing with lipoprotein (LP) metabolism and fate have employed radioiodinated preparations wherein the radionuclide is affixed to surface or core components of the LPs. Since the apolipoproteins are a critical component in the interaction of LPs with cellular receptors, others have sought ways to radiolabel the core rather than the surface elements of LPs. The rapid metabolism of radioiodinated LPs when administered in vivo has led investigators to develop radioiodinated markers that would not be degraded by proteolytic enzymes upon uptake within cells. One method used to package exogenous cholesteryl esters into LPs is to allow the test animal to incorporate the compound into its own lipoproteins. Incorporation of radiopharmaceuticals into the neutral lipid core of LPs requires the use of methodologies that permit passage of the lipophilic molecule through the LP’s outer hydrophilic layer of apoproteins and polar lipids.
