Effect of synthetic atrial natriuretic factor on aldosterone secretion in the rat

Direct in vivo measurements of aldosterone secretion were made before and after infusion of synthetic rat atrial natriuretic factor (ANF) into anesthetized rats with markedly different levels of plasma renin activity. Infusion of ANF peptide at 350 ng . kg-1 . min-1 significantly decreased aldosterone secretion by 32% and plasma renin activity by 55% in rats that had been maintained on a normal-sodium diet. Similar reductions in aldosterone secretion and plasma renin activity were observed in hyperreninemic rats after chronic sodium restriction. Infusion of ANF at 350 ng . kg-1 . min-1 into anephric rats with low circulating levels of renin did not significantly decrease the secretion of aldosterone. Increasing the ANF peptide infusion dose fivefold in these anephric rats did result in a significant reduction in aldosterone secretion, but this higher dose also produced significant decreases in blood pressure not observed with the lower dose of ANF. These results demonstrate that infusion of synthetic ANF decreases the secretion rate of aldosterone in the rat, but the ability of ANF to decrease aldosterone secretion is attenuated when circulatory levels of renin and hence angiotensin II are very low. The data suggest that although ANF can exert a direct inhibitory effect on the adrenal glomerulosa in larger doses that also produce systemic cardiovascular effects, one physiological mechanism by which ANF suppresses aldosterone secretion may be related indirectly to the inhibition of renin release.