Oxidation-induced loss of the ability of HDL to counteract the inhibitory effect of oxidized LDL on vasorelaxation

Several current diseases are associated with an increase in the oxidation of HDL, which is likely to impair their functionality. Our aim was to identify whether oxidation could change the protective effect of HDL against the deleterious effect on vasoreactivity induced by oxidative stress. HDL from healthy subjects were oxidized in vitro by Cu 2+ , and the ability of oxidized HDL to counteract the inhibitory effect of oxidized LDL on acetylcholine-induced vasodilation was tested on isolated rabbit aorta rings. Oxidation of HDL was evidenced by the increase in the 7-oxysterols/cholesterol ratio (3.20 ± 1.12 vs 0.02 ± 0.01 % in native HDL, p