AT1 receptors: coronary flow and flow reserve.

Angiotensin II, through its effects at the angiotensin-type 1 receptor, elevates arterial pressure and exacerbates hypertensive heart disease. Alterations in coronary hemodynamics, including reductions in coronary blood flow and flow reserve promotes coronary insufficiency and contributes to the increased cardiovascular risk associated with these conditions. In spontaneously hypertensive rats, coronary flow reserve, the difference between basal coronary blood flow and the flow achieved during maximal coronary vasodilation achieved by dipyridimole, was increased to a greater extent after treatment for 3 months with an angiotensin II receptor blocker as compared with an angiotensin converting enzyme inhibitor. The combination of the two agents, in equidepressor doses, almost restored coronary flow reserve to levels seen in normotensive Wistar Kyoto rats. This finding suggests a possible advantage of combination angiotensin converting enzyme inhibitors and angiotensin II receptor blocker therapy in patients with hypertension and hypertensive heart disease.