SPECIFICITY AND MECHANISM OF FATTY-ACID INHIBITION OF ALDOSTERONE SECRETION

We have shown that unesterified, unsaturated long-chain fatty acids in hibit angiotensin II (AII) binding to receptors in adrenal glomerulosa cells, In this report, we show that oleic and arachidonic acids are s pecific inhibitors of the AT(1) subtype of angiotensin receptor, and e xert no effect on receptors of the AT(2) subtype. By contrast, decanoi c acid is a weak inhibitor of the AT(2) subtype only, Our previous wor k on a post-receptor locus of inhibition by fatty acids of aldosterone biosynthesis showed that the 18-oxidase step is uniquely sensitive, I n brief, the first and last steps involved in angiotensin-stimulated a ldosterone secretion are particularly sensitive to inhibition by fatty acids. These results suggest a specific role for unesterified fatty a cids in regulation of salt and water metabolism.