Effect of oxidized LDL on erythrocyte nitric oxide metabolism.

AIMS: Oxidized low density lipoprotein (ox-LDL) has been reported as an inhibitor of nitric oxide (NO)-mediated dilatation in microcirculation. Oxidized LDL effect on NO metabolism of erythrocytes is not known. Therefore, this study aims to evaluate the effect of ox-LDL on erythrocytes NO metabolism. METHODS: The effect of different concentrations of human purified ox-LDL (25, 50 and 100 mu g/mL) on NO metabolism was evaluated on blood of healthy subjects. RESULTS: An inhibitory effect of higher concentrations of ox-LDL on erythrocyte NO efflux levels was verified. Concentrations of NO efflux from erythrocytes were lower as consequence of treatments with 50 mu g/mL ox-LDL treatment (1.6 +/- 0.27 nM) and 100 mu g/mL ox-LDL treatment (1.3 +/- 0.22 nM) than control (1.9 +/- 0.28 nM). Opposite, ox-LDL incubation has a positive effect on GSNO content of erythrocytes. That effect is proportional to concentrations of ox-LDL treatments (10.8 +/- 1.4 nM for 25 mu g/mL, 12.9 +/- 1.5 nM for 50 mu g/mL and 12.1 +/- 1.9 nM for 100 mu g/mL) and is significant relative to control (8.56 +/- 0.76 mu M) and ACh (8.9 +/- 0.52 mu M) aliquots. CONCLUSIONS: Presence of oxidized LDL in erythrocyte NO metabolism induces a decrease of NO efflux amount and an increase on intra-erythrocyte GSNO concentrations. These results suggest a role of ox-LDL in mobilization of NO between NO derivatives molecules in dependence of oxidized LDL concentration. An anti-reactive nitrogene role can be attributed to ox-LDL for its contribution in the erythrocyte scavenged ability for nitric oxide.