The binding of oxidized low density lipoprotein (ox-LDL) to ox-LDL receptor-1 reduces the intracellular concentration of nitric oxide in endothelial cells through an increased production of superoxide.
Oxidized low density lipoprotein (ox-LDL) has been suggested to affect endothelium-dependent vascular tone through a decreased biological activity of endothelium-derived nitric oxide (NO). Oxidative inactivation of NO is regarded as an important cause of its decreased biological activity, and in this context superoxide (O(2)) is known to inactivate NO in a chemical reaction during which peroxynitrite is formed. In this study we examined the effect of ox-LDL on the intracellular NO concentration in bovine aortic endothelial cells and whether this effect is influenced by ox-LDL binding to the endothelial receptor lectin-like ox-LDL receptor-1 (LOX-1) through the formation of reactive oxygen species and in particular of O(2). ox-LDL induced a significant dose-dependent decrease in intracellular NO concentration both in basal and stimulated conditions after less than 1 min of incubation with bovine aortic endothelial cells (p < 0.01). In the same experimental conditions ox-LDL also induced O(2) generation (p < 0.001). In the presence of radical scavengers and anti-LOX-1 monoclonal antibody, O(2) formation induced by ox-LDL was reduced (p < 0.001) with a contemporary rise in intracellular NO concentration (p < 0.001). ox-LDL did not significantly modify the ability of endothelial nitric oxide synthase to metabolize l-arginine to l-citrulline. The results of this study show that one of the pathophysiological consequences of ox-LDL binding to LOX-1 may be the inactivation of NO through an increased cellular production of O(2).
Department of Biomedical and Surgical Sciences, Verona University, 37134 Verona, Italy. comina@medicinad.univr.it
L
L
Cominacini
A
A
Rigoni
A F
AF
Pasini
U
U
Garbin
A
A
Davoli
M
M
Campagnola
A M
AM
Pastorino
V
V
Lo Cascio
T
T
Sawamura
D000493:Allopurinol / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D001011:Aorta / Q000378:metabolism; D001205:Ascorbic Acid / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology; D001920:Bradykinin / Q000494:pharmacology; D016466:CHO Cells; D002395:Catecholamines / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D002839:Chromans / Q000494:pharmacology; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D016166:Free Radical Scavengers / Q000494:pharmacology; D006490:Hemostatics / Q000494:pharmacology; D006801:Humans; D048288:Imidazolines; D008077:Lipoproteins, LDL / Q000378:metabolism*; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D011341:Probucol / Q000494:pharmacology; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000378:metabolism; D011973:Receptors, LDL / Q000378:metabolism*; D051131:Receptors, Oxidized LDL; D051127:Scavenger Receptors, Class E; D013481:Superoxides / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology; D013997:Time Factors; D019323:omega-N-Methylarginine / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D000975:Antioxidants; D002395:Catecholamines; D002839:Chromans; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D006490:Hemostatics; D048288:Imidazolines; D008077:Lipoproteins, LDL; C495137:OLR1 protein, human; C495138:Olr1 protein, mouse; D017382:Reactive Oxygen Species; D011973:Receptors, LDL; D051131:Receptors, Oxidized LDL; D051127:Scavenger Receptors, Class E; C099252:oxidized low density lipoprotein; D013481:Superoxides; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D000493:Allopurinol; C011775:(3,4-dihydroxyphenylamino)-2-imidazoline; D013917:Thrombin; D011341:Probucol; D001205:Ascorbic Acid; D001241:Aspirin; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; D010100:Oxygen; D001920:Bradykinin