This study investigated the ability of angiotensin I (Ang I) to facilitate the stimulation induced release of 3H-norepinephrin (3H-NE) from two cardiovascular regulatory areas in normal and sodium restricted rats. Ang I (10~7M) facilitated the stimulation induced release of 3H-NE from the A2 area of the nucleus tractus solita-rius but not from the anterior hypothalamus of Sprague-Dawley and Wistar rats. Placement of rats on a sodium restricted diet blocked the facilitation of 3H-NE release due to Ang I . Captopril given with the sodium restricted diet partially restored the facilitory effect of Ang I . Chronic I V Ang II infusions blocked the facilitory effect of Ang II on 3H-NE release in a manner similar to that seen with sodium restriction. These results suggest that low sodium diets may alter the facilitation of 3H-NE release by Ang I by interactions with the renin-angiotensin system.