Aldosterone and renin inhibition by physiological levels of atrial natriuretic factor

This study was designed to examine, in the rat, the inhibition of renin release and aldosterone secretion by physiological plasma levels of atrial natriuretic factor (ANF). Intravascular volume expansion over 30 min with donor blood equal to 3% body weight increased plasma ANF concentration from a base line of 216 +/- 28 to 1,590 +/- 240 pg/ml (P less than 0.001) in sodium-replete rats. Basal plasma ANF levels were decreased to 125 +/- 9 pg/ml in animals fed a low-sodium diet, and the infusion of synthetic ANF into separate groups of these rats at doses of 15 or 45 ng.kg-1.min-1 elevated plasma ANF to 346 +/- 38 and 720 +/- 96 pg/ml, respectively (P less than 0.001 for both values). Infusion of ANF at 15 ng.kg-1.min-1 resulted in a significantly lower plasma renin activity 30 +/- 3 vs. 69 +/- 5 ng angiotensin I (ANG I).ml-1.h-1, P less than 0.05, but there was no difference in aldosterone secretion between control and infused groups (7.00 +/- 0.49 vs. 7.29 +/- 0.95 ng/min, P greater than 0.05). However, the higher ANF dose of 45 ng.kg-1.min-1 did reduce aldosterone secretion approximately 40% to 4.18 +/- 0.36 ng/min (P less than 0.001) with no further suppression in plasma renin activity. In sodium-replete rats, infusion of ANF at 45 ng.kg-1.min-1 resulted in lower plasma renin activity compared with the control noninfused group (14 +/- 4 vs. 22 +/- 2 ng ANG I.ml-1.h-1, P less than 0.05), but aldosterone secretion was not different (P greater than 0.05) between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)