Oxidized-LDL induced changes in membrane physico-chemical properties and [Ca2+]i of bovine aortic endothelial cells. Influence of vitamin E.
The effects of 3 days' exposure to native and oxidatively modified human low density lipoprotein (LDL and Ox-LDL) on cultured bovine aortic endothelial cell cholesterol content, membrane microviscosity and intracellular free calcium concentration ([Ca2+]i) were studied. Free cholesterol content increased by 35% and 100% in LDL and Ox-LDL treated cells, respectively, these effects being reversed by vitamin E; esterified cholesterol, which rose by 110% in the Ox-LDL group only, was not affected by vitamin E. Membrane microviscosity, measured as the fluorescence polarization of the trimethylammonium derivative of diphenyl-hexatriene, increased by 9% in Ox-LDL treated cells only. This effect was also reversed by vitamin E. Using the calcium sensitive fluorescent dye fura 2-AM, increases in basal [Ca2+]i of 36% in LDL and 81% in Ox-LDL treated cells were observed. The bradykinin mediated increase in [Ca2+]i was enhanced in both the LDL and, to a greater extent, the Ox-LDL group. Vitamin E reversed the effects of LDL on [Ca2+]i but had no influence in the Ox-LDL group. The lipoproteins affected all parameters measured in this study. Oxidized LDL produced reversible and irreversible alterations to the membrane and the [Ca2+]i. All changes associated with LDL were abolished by vitamin E. Such modifications in the physicochemical properties of the membrane and [Ca2+]i could be involved in the initiation of the atherosclerotic process.
Thorin
E
E
Department of Medicine and Therapeutics, University of Glasgow, Gardiner Institute, Western Infirmary, UK.
Hamilton
C
C
Dominiczak
A F
AF
Dominiczak
M H
MH
Reid
J L
JL
D000818:Animals; D001011:Aorta / Q000166:cytology* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism*; D008074:Lipoproteins / Q000378:metabolism*; D010084:Oxidation-Reduction; D014783:Viscosity; D014810:Vitamin E / Q000494:pharmacology*
D008074:Lipoproteins; D014810:Vitamin E; D002784:Cholesterol; D002118:Calcium