Hypochlorite-modified low density lipoprotein inhibits nitric oxide synthesis in endothelial cells via an intracellular dislocalization of endothelial nitric oxide synthase

摘要: Hypochlorous acid/hypochlorite, generated by the myeloperoxidase/H(2)O(2)/halide system of activated phagocytes, has been shown to oxidize/modify low density lipoprotein (LDL) in vitro and may be involved formation atherogenic lipoproteins vivo. Accordingly, hypochlorite-modified (lipo)proteins have detected human atherosclerotic lesions where they colocalize with macrophages endothelial cells. The present study investigates influence LDL on synthesis nitric oxide (NO) measured as citrulline (coproduct NO) cGMP (product NO-activated soluble guanylate cyclase) upon cell stimulation thrombin or ionomycin. Pretreatment umbilical vein cells led a time- concentration-dependent inhibition agonist-induced compared preincubation native LDL. This was neither due decreased expression NO synthase (eNOS) nor deficiency its cofactor tetrahydrobiopterin. Likewise, uptake l-arginine, substrate eNOS, into not affected. Hypochlorite-modified caused remarkable changes intracellular eNOS distribution including translocation from plasma membrane disintegration Golgi location without altering myristoylation palmitoylation enzyme. In contrast, cyclodextrin known deplete cholesterol disrupt caveolae induced only disappearance that associated formation. findings suggest mislocalization NOS accounts for reduced treated point an important role Golgi-located these processes. We conclude mechanism development dysfunction early pathogenesis atherosclerosis.