Journal of Lipid Research, Vol 33, 1373-1382, Copyright © 1992 by Lipid Research, Inc.
Effect of phospholipid fatty acid composition of endothelial cells on cholesterol efflux rates
EP Kilsdonk, AN Dorsman, T van Gent and A van Tol
Department of Biochemistry, Faculty of Medicine and Health Sciences, Erasmus University Rotterdam, The Netherlands.
Human endothelial cells (EA.hy 926 line) were loaded with cationized low
density lipoprotein (LDL) and subsequently incubated with fatty acid/bovine
serum albumin complexes. The fatty acids were palmitic, oleic, linoleic,
arachidonic, and eicosapentaenoic acids. The preincubations resulted in
extensively modified fatty acid profiles in cell membrane phospholipids and
in cellular cholesteryl esters. The cholesterol efflux from these fatty
acid-modified cells was measured using 0.2 mg high density lipoprotein3
(HDL3)/ml medium. The efflux was significantly higher for the palmitic
acid-treated cells, compared to all other fatty acid treatments. These
differences in efflux rates were not caused by changes in the binding of
HDL3 to high affinity receptors on the EA.hy 926 cells. Efflux mediated by
dimethyl suberimidate- treated HDL3, which does not interact with high
affinity HDL receptors, was similar to efflux induced by native HDL3 after
all fatty acid treatments. Our results indicate that high affinity HDL
receptors are not important for HDL-mediated efflux of cell cholesterol.
The fatty acid composition of the cell membrane phospholipids may be an
important determinant.