Angiotensin II is a hormone that plays an important role in regulating blood pressure. Elevated levels of angiotensin II are implicated in inducing and maintaining hypertension, and also in the development of atherosclerosis. Both of these effects are mediated by the angiotensin II type 1 (AT) receptor. Losartan is a mammalian AT receptor antagonist with a K value of 5-20 nM. In humans, losartan effectively controls hypertension while protecting renal function. Nitric oxide (NO) causes vasodilation and also inhibits platelet and neutrophil aggregation in the endothelium. NO-losartan A possesses similar anti-hypertensive effects to losartan, with the addition of the vasodilating effects of NO release.