Lack of atrial natriuretic peptide receptors in human aldosteronoma

The effect of synthetic alpha-human atrial natriuretic peptide (ANP) on aldosterone secretion was studied in human aldosterone producing adrenocortical adenoma obtained surgically from a patient with primary aldosteronism and in human apparently normal adjacent adrenal cortical tissues obtained from a patient with pheochromocytoma, in vitro. Apparently normal adrenal cortical tissue responded to ANP with the known inhibition of aldosterone secretion. In contrast, the aldosterone producing adenoma did not respond to ANP. When stimulated by either ACTH or angiotensin II, there is no inhibition by ANP in the adenoma tissue, whereas normal tissue was inhibited. Immunohistochemical examination utilizing an ANP-receptor antiserum demonstrated that there was no evidence of binding site in the cortical adenoma, in contrast, zona glomerulosa cells in the cortical tissues adjacent to either aldosterone producing adenoma or pheochromocytoma were densely stained. This apparent lack of ANP-receptors is an associated finding with the hypersecretion of aldosterone in the aldosterone producing adenoma.