Lack of Inhibitory Effect of α-Human Atrial Natriuretic Polypeptide on Aldosteronogenesis in Aldosterone-Producing Adenoma

The effects of synthetic aαhuman atrial natriuretic polypeptide (αhANP) on aldosteronogenesis in normal and aldosterone-producing adenoma cells (APA cells) in primary monolayer cultures were studied. αhANP significantly inhibited aldosterone secretion from normal adrenal cells in culture, but had no inhibitory effect on aldosterone secretion from APA cells in the presence or absence of 10-8 M ACTH. αhANP enhanced the accumulation of intracellular cGMP in normal adrenal cells in culture, but not in APA cells. Visualization of [125I]iodoahANP-specific binding sites in APA and adjacent normal adrenal tissues by an in vitro receptor autoradiographic technique showed that these sites were localized only in normal adrenal tissue, but not in APA tissue. These results suggest that the lack of an inhibitory effect of ahANP on aldosteronogenesis in APA cells may be due to the absence of ahANP–specific receptor sites in APA cells.