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 3
HDL-associated estradiol is responsible for eNOS stimulation. (a) HDL was isolated from female C57BL/6 mice that had intact ovaries (Intact), had the ovaries removed (OVX), or had the ovaries removed and a 17-β-estradiol pellet implanted (OVX + E2). HDL was also isolated from male age-matched C57BL/6 mice that had a 17-β-estradiol pellet implanted (Male + E2). In addition, HDL from control male mice was isolated and enriched with 17-β-estradiol in vitro (Male HDL + E2). LDL from female mice (LDL + E2) and BSA (BSA + E2) were also enriched with 17-β-estradiol in vitro. The in vitro–modified HDL, LDL, and BSA were reisolated, and the amount of estradiol associated was quantified before use (see Methods). Human microvascular endothelial cells were pretreated with 0.75 μCi/ml of [³H]arginine, followed by treatment with 10 μg/ml of each sample or 1 μg/ml of ionomycin for 15 minutes at 37°C. The cells were then processed to quantify the amount of citrulline generated. 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). The data are from eight independent experiments, with triplicate measurements in each experiment (mean ± SE). (b) The same assay as described above was used, with the exception that 10 μM of ICI 182,780 was added to each of the reactions. The data are from four independent experiments, with triplicate measurements in each experiment (mean ± SE).