The main findings of this study are that 6β-OHT, a metabolite of testosterone generated by CYP1B1, contributes to the effects of Ang II to (1) increased vascular reactivity to PE and ET-1, (2) endothelial dysfunction, (3) vascular hypertrophy, (4) vascular fibrosis, and (5) oxidative stress. The gene discussed is EDN1; the disease is endothelial dysfunction.