Aluminum ions stimulate the oxidizability of low density lipoprotein by Fe2+: implication in hemodialysis mediated atherogenic LDL modification.
OBJECTIVE
Al(3+) stimulates Fe(2+) induced lipid oxidation in liposomal and cellular systems. Low-density lipoprotein (LDL) oxidation may render the particle atherogenic. As elevated levels of Al(3+) and increased lipid oxidation of LDL are found in sera of hemodialysis patients, we investigated the influence of Al(3+) on LDL oxidation.


METHODS
Using different LDL modifying systems (Fe(2+), Cu(2+), free radical generating compounds, human endothelial cells, hemin/H(2)O(2) and HOCl), the influence of Al(3+) on LDL lipid and apoprotein alteration was investigated by altered electrophoretic mobility, lipid hydroperoxide-, conjugated diene- and TBARS formation.


RESULTS
Al(3+) could stimulate the oxidizability of LDL by Fe(2+), but not in the other systems tested. Al(3+) and Fe(2+) were found to bind to LDL and Al(3+)could compete with Fe(2+) binding to the lipoprotein. Fluorescence polarization data indicated that Al(3+) does not affect the phospholipid compartment of LDL.


CONCLUSIONS
The results indicate that increased LDL oxidation by Fe(2+) in presence of Al(3+) might be due to blockage of Fe(2+) binding sites on LDL making more free Fe(2+) available for lipid oxidation.
Kapiotis
Stylianos
S
Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Vienna, Austria.
Hermann
Marcela
M
Exner
Markus
M
Sturm
Brigitte N
BN
Scheiber-Mojdehkar
Barbara
B
Goldenberg
Hans
H
Kopp
Stefan
S
Chiba
Peter
P
Gmeiner
Bernhard M K
BM
D000535:Aluminum / Q000737:chemistry*; D050197:Atherosclerosis; D002478:Cells, Cultured; D003300:Copper / Q000737:chemistry; D004586:Electrophoresis; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D005609:Free Radicals; D006427:Hemin / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D050356:Lipid Metabolism; D015227:Lipid Peroxidation; D008055:Lipids / Q000737:chemistry; D008074:Lipoproteins / Q000737:chemistry; D008077:Lipoproteins, LDL / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D006435:Renal Dialysis; D013050:Spectrometry, Fluorescence; D017392:Thiobarbituric Acid Reactive Substances; D013997:Time Factors
D005609:Free Radicals; D007477:Ions; D008055:Lipids; D008074:Lipoproteins; D008077:Lipoproteins, LDL; D017392:Thiobarbituric Acid Reactive Substances; D006427:Hemin; D003300:Copper; D006861:Hydrogen Peroxide; D000535:Aluminum; D007501:Iron; D010100:Oxygen