ANGIOTENSIN-II RECEPTOR SUBTYPES AND CARDIAC-FUNCTION

All the components of the renin-angiotensin system have been identified in the heart including the angiotensin II receptor subtypes AT(1) and AT(2). In the normal human heart, there is a decreasing receptor density from the right atrium to the left ventricle. In right atrial membranes prepared from pathological hearts, the percentage of AT(1) receptor decreases with the severity of cardiac dysfunction whereas that of AT(2) receptor increases. Treatment of hypertrophic rats with ATI receptor antagonists inhibits cardiac hypertrophy and reverses the increase receptor density, indicating involvement of this Ang II receptor subtype. The role of the AT(2) receptor is still largely unknown but it may be involved in cell growth and proliferation. The cloning of both ATI and AT, receptors as well as the availability of potent and selective antagonists will help os to understand better the functional role of Angiotensin II in cardiovascular disorders.