Biomaterial Database

Rate of exchange of esterified cholesterol between human plasma low and high density lipoproteins. 1979

P J Barter, and M E Jones

In vitro incubations of human low density lipoproteins (LDL), high density lipoproteins (HDL) and lipoprotein-free plasma at 37 degrees for 6 h revealed no significant net mass transfers of esterified cholesterol from either lipoprotein fraction to the other. Observed transfers of esterified [3H]cholesterol from LDL to HDL must, therefore, have represented a process of molecular exchange between the two fractions. The time course of the esterified [3H]cholesterol transfers indicated that, from the point of view of the exchange process, the pools of esterified cholesterol in LDL and HDL were (mathematically) homogeneous, thus permitting a precise calculation of the rate of the exchange between the two fractions. In incubations of lipoproteins isolated from the plasma of 9 clinically normal human subjects, there was an hourly exchange of 8-12% and 7-31% of the pools of esterified cholesterol in LDL and HDL respectively, which, in molar terms, represented an exchange of 108-301 mumol/l plasma/h between the two fractions. The exchange of esterified cholesterol between human LDL and HDL is, therefore, rapid when considered in relation to other parameters of esterified cholesterol and lipoprotein metabolism.

UI	MeSH Term	Description	Entries
D008075	Lipoproteins, HDL	A class of lipoproteins of small size (4-13 nm) and dense (greater than 1.063 g/ml) particles. HDL lipoproteins, synthesized in the liver without a lipid core, accumulate cholesterol esters from peripheral tissues and transport them to the liver for re-utilization or elimination from the body (the reverse cholesterol transport). Their major protein component is APOLIPOPROTEIN A-I. HDL also shuttle APOLIPOPROTEINS C and APOLIPOPROTEINS E to and from triglyceride-rich lipoproteins during their catabolism. HDL plasma level has been inversely correlated with the risk of cardiovascular diseases.	High Density Lipoprotein,High-Density Lipoprotein,High-Density Lipoproteins,alpha-Lipoprotein,alpha-Lipoproteins,Heavy Lipoproteins,alpha-1 Lipoprotein,Density Lipoprotein, High,HDL Lipoproteins,High Density Lipoproteins,Lipoprotein, High Density,Lipoprotein, High-Density,Lipoproteins, Heavy,Lipoproteins, High-Density,alpha Lipoprotein,alpha Lipoproteins
D008077	Lipoproteins, LDL	A class of lipoproteins of small size (18-25 nm) and light (1.019-1.063 g/ml) particles with a core composed mainly of CHOLESTEROL ESTERS and smaller amounts of TRIGLYCERIDES. The surface monolayer consists mostly of PHOSPHOLIPIDS, a single copy of APOLIPOPROTEIN B-100, and free cholesterol molecules. The main LDL function is to transport cholesterol and cholesterol esters to extrahepatic tissues.	Low-Density Lipoprotein,Low-Density Lipoproteins,beta-Lipoprotein,beta-Lipoproteins,LDL(1),LDL(2),LDL-1,LDL-2,LDL1,LDL2,Low-Density Lipoprotein 1,Low-Density Lipoprotein 2,LDL Lipoproteins,Lipoprotein, Low-Density,Lipoproteins, Low-Density,Low Density Lipoprotein,Low Density Lipoprotein 1,Low Density Lipoprotein 2,Low Density Lipoproteins,beta Lipoprotein,beta Lipoproteins
D002784	Cholesterol	The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.	Epicholesterol
D004951	Esterification	The process of converting an acid into an alkyl or aryl derivative. Most frequently the process consists of the reaction of an acid with an alcohol in the presence of a trace of mineral acid as catalyst or the reaction of an acyl chloride with an alcohol. Esterification can also be accomplished by enzymatic processes.	Esterifications
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor