HDL-associated estradiol stimulates endothelial NO synthase and vasodilation in an SR-BI–dependent manner
J. Clin. Invest. Ming Gong, et al. 111:1579 doi:10.1172/JCI16777 [Go to this article.]

Figure 1
HDL isolated from female subjects stimulates the production of nitric oxide. HDL, LDL, and VLDL were isolated from young, reproductively competent female humans (a) and mice (b) and age-matched male humans (a) and mice (b) (31). The freshly isolated lipoproteins (10 μg/ml) were incubated with human microvascular endothelial cells that had been prelabeled with 0.75 μCi/ml of [³H]arginine for 15 minutes at 37°C (21). An additional set of cells was treated with 1 μg/ml of ionomycin to determine the maximal eNOS stimulation. The cells were then washed, lysed, and extracted, and radiolabeled arginine was separated from radiolabeled citrulline using an ion-exchange column. Each experiment included controls, using 1 mM L-NNA to demonstrate that over 99% of the generated citrulline was due to eNOS activity (data not shown). In (c), a concentration curve of the effect of female HDL on eNOS activity is shown. The data are from six to eight independent experiments, with triplicate measurements in each experiment (mean ± SE).