Angiotensin II modulation of the arterial baroreflex: role of the area postrema

1. Resetting the operating point of the arterial baroreflex appears to be an important factor involved in determining the level of sympathetic outflow. 2. Substantial data indicate that circulating angiotensin (Ang)II can reset the arterial baroreflex to higher operating pressures. 3. This action of AngII to increase the level of sympathetic nervous system outflow relative to blood pressure may contribute to elevated mean arterial pressure (MAP) during AngII hypertension, as well as to the maintenance of MAP during low sodium states. 4. In most instances, the resetting observed during elevated peripheral AngII is dependent on the area postrema (AP). 5. Although the central mechanisms by which the arterial baroreflex resets to different operating pressures remain to be completely defined, the AP may provide a separate mechanism whereby humoral factors can modulate the operating point of the arterial baroreflex.