In vitro metabolism of LDL labeled with a nondegradable cholesteryl ester analogue

Journal Article · · Arteriosclerosis (Dallas); (United States)

DOI:https://doi.org/10.1161/01.ATV.4.3.208· OSTI ID:7008012

Higgs, D W; van der Westhuyzen, D R; Gevers, W; Coetzee, G A; Stein, O; Stein, Y

Low density lipoprotein (LDL) metabolism by human skin fibroblasts was studied using LDL labeled in the neutral lipid fraction with a nonhydrolysable cholesteryl ester analogue /sup 3/H-cholesteryl linoleyl ether (/sup 3/H-CLE-LDL). LDL uptake could be quantitated accurately using /sup 3/H-CLE-LDL, since the label accumulated intracellularly due to its resistance to hydrolysis. /sup 3/H-CLE-LDL was taken up via apo B,E receptor-mediated endocytosis in a manner similar to /sup 125/I-labeled LDL. This was demonstrated by similar rates of uptake of the two differently labeled LDL preparations, saturation kinetics of uptake with respect to /sup 3/H-CLE-LDL concentration, regulation of /sup 3/H-CLE-LDL uptake by procedures that up-regulate or down-regulate the number of apo B,E receptors, and negligible uptake of /sup 3/H-CLE-LDL by receptor-negative cell strains. The major difference between the handling of /sup 125/I-LDL and /sup 3/H-CLE-LDL was the finding that, while the amount of trypsin-releasable (surface) /sup 3/H-CLE increased progressively over a 24-hour experimental period, trypsin-releasable /sup 125/I-LDL reached a maximum within 30 minutes. After 24 hours of incubation, the /sup 3/H radioactivity released by brief trypsinization was three to four times higher than could be accounted for by /sup 125/I radioactivity released by a similar treatment. Possible reasons for this behavior are discussed.

• Research Organization: UCT/MRC Muscle Research Unit, UCT Medical School, South Africa
• OSTI ID: 7008012
• Journal Information: Arteriosclerosis (Dallas); (United States), Journal Name: Arteriosclerosis (Dallas); (United States) Vol. 4:3; ISSN ARTRD
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CHOLESTEROL
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
FIBROBLASTS
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLED COMPOUNDS
LIPIDS
LIPOPROTEINS
METABOLISM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
SOMATIC CELLS
STEROIDS
STEROLS
TRACER TECHNIQUES
TRITIUM COMPOUNDS