Abstract P218: Induction of Human Endothelin-1 Overexpression for 3 Months Causes Blood Pressure Rise and Small Artery Endothelial Dysfunction and Stiffening

Background: The mechanisms of blood pressure (BP) regulation by endothelin (ET)-1 produced by endothelial cells are complex and remain unclear. Recently, we developed a transgenic mouse with tamoxifen-inducible endothelium-restricted human ET-1 overexpression (ieET-1) using Cre/loxP technology. ieET-1 mice exhibited BP rise after three weeks of induction in an ET type A (ET A ) receptor-dependent manner, in absence of vascular and kidney injury. It is unknown whether long-term exposure to ET-1 overexpression results in sustained BP elevation and vascular injury. Design and methods: Nine to 12-week old male ieET-1 mice and control ieCre mice expressing a tamoxifen-inducible Cre recombinase under the control of endothelium-specific Tie2 promoter, were treated with tamoxifen (1 mg/kg/day, s.c.) for 5 days and studied 3 months later. ieET-1 mice were treated or not with ET A receptor blocker, atrasentan (10 mg/kg/day, PO) in the last 2 weeks of the study. BP by telemetry, endothelial function and vascular remodeling by pressurized myography and reactive oxygen species (ROS) generation using dihydroethidium staining in mesenteric artery (MA) or perivascular fat (PVAT) and renal artery flow (RAF) by ultrasonography were determined. Results: Systolic BP was increased in ieET-1 and normalized by atrasentan compared to ieCre mice (141±0 and 124±4 vs 120±0 mm Hg, P P P 2 , P P Conclusions: Long-term exposure to endothelial human ET-1 overexpression caused sustained BP elevation, endothelial dysfunction and vascular stiffening and oxidative stress.