Angiotensin II is a hormone that plays an important role in regulating blood pressure.{9986} 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 (AT1) receptor.{12999} Losartan is a mammalian AT1 receptor antagonist with a Ki of 5-20 nM.{12997} In humans, losartan effectively controls hypertension while protecting renal function.{12996} NO causes vasodilation and also inhibits platelet and neutrophil aggregation in the endothelium.{6818,13090} NO-losartan A possesses similar anti-hypertensive effects to losartan, with the addition of the vasodilating effects of NO release.{12442}