Hypertension Induction and Aortic Analysis

All animal studies were approved by the Institutional Animal Care and Use Committee of Vanderbilt University. Briefly, hypertension was induced in male wild-type mice (C57BL/6; Jackson Laboratories) at 3 months of age via chronic infusion of angiotensin-II (Ang II; Sigma-Aldrich) at a continuous rate of 490 ng/kg/min for 2 or 4 weeks using an osmotic mini-pump (Alzet). This pump was implanted subcutaneously on the flank under sterile conditions during a brief surgery in which Ketoprofen (5 mg/kg) was used for pre-anesthesia and ketamine (100mg/kg) and xylazine and 10 (mg/kg) was used for anesthesia. Blood pressure was measured every hour over the up to 4-week study period via an indwelling catheter and telemetry system (Figure S1). At the prescribed endpoint, the mice were euthanized by CO₂ inhalation and the descending thoracic aorta was excised from the left subclavian artery to the third pair of intercostal branches. Age-matched control vessels were obtained similarly, but following a Sham procedure wherein the implanted mini-pumps released normal saline rather than Ang II. Additional details can be found elsewhere.^{1 (link)}The Online Data Supplement describes established methods for biaxial mechanical testing, quantitative histology, and computing wall stress, material stiffness, (an intrinsic property of the wall), structural stiffness (which depends on material stiffness and geometry), and stored energy (http://hyper.ahajournals.org).