Losartan Administration (Night before and t = 0, t = 5) Losartan is a novel orally available FDA-approved drug that pharmacologically inhibits the renin-angiotensin-aldosterone system. In particular, its primary mechanism of action is to inhibit production of the vasoconstrictor angiotensin II. It has a strong record of safety and efficacy and benefits patients with all grades of heart failure. losartan dosing is not based on individual body weight. The max dosing regimen proposed (25 mg losartan/day) is predicted to drop systolic blood pressure by approximately 5-12 mmHg and diastolic by 4-8 mmHg. The response is expected to be most profound among individuals with the highest systolic blood pressure. For safety purposes the investigators will administer losartan at 25 mg BID.