Metabolic Fate of 3H-Cholesteryl Linoleyl Ether, a Nondegradable Analog of Lipoprotein Cholesteryl Ester
Studies in the past have pointed out that in the human during the intravascular metabolism of very low density lipoproteins (VLDL) which culminates in the formation of low density lipoproteins (LDL) there is a considerable loss of cholesteryl ester (1). To follow the fate of cholesteryl ester during the metabolism of VLDL, various approaches were used to label the lipid portion of the lipoprotein. These can be divided into two main categories, i.e., endogenous labeling and exogenous labeling. The first was based on the injection of crystalline suspensions of labeled cholesterol of high specific activity which following uptake by the liver reappears in the VLDL secreted into plasma in the form of free and esterified cholesterol. One can remove the free cholesterol by exchange following incubation with erythrocytes, but this procedure changes the biological behavior of the lipoprotein (2) and also leaves a considerable portion of unesterified labeled cholesterol. Another approach utilizes the LCAT reaction in vitro to convert exogenously added labeled free cholesterol to cholesteryl ester, but this reaction as well does not go to completion. Therefore, several methods were developed to label lipoproteins with pure labeled cholesteryl ester by the introduction of the lipid into the lipoprotein in vitro (3).
KeywordsHigh Density Lipoprotein Cholesteryl Ester Cholesteryl Ester Transfer Protein Cholesteryl Linoleate Oleyl Ether
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