Oxidized lipoprotein(a) inhibits endothelium-dependent dilation: prevention by high density lipoprotein

We assessed the effects of human native and oxidized lipoprotein(a) (150 min, 30 and 100 micrograms/ml) on endothelium-dependent vasodilation of isolated rabbit renal arteries. Vasodilation was not attenuated after incubation of arteries with native lipoprotein(a). However, when the arteries were exposed to oxidized lipoprotein(a), acetylcholine-induced vasodilation was dose dependently significantly impaired. Concomitant incubation of segments with high density lipoprotein (HDL, 0.5 mg/ml) prevented the attenuation of dilations induced by oxidized lipoprotein(a). Thus, we report for the first time that oxidized lipoprotein(a) impairs endothelium-dependent vasodilation, and that HDL prevents its inhibitory effect.