Membrane Receptors for Aldosterone: a Novel Pathway for Mineralocorticoid Action

Rapid nongenomic in vitro effects of aldosterone on intracellular electrolytes, cell volume, and Na(+)-H+ antiport have been found in human mononuclear leukocytes (HML). Binding of 125I-labeled aldosterone to plasma membranes of HML shares important features with these functional data. This includes a very low apparent dissociation constant (Kd) of 0.1 nM for both aldosterone and the effect on the Na(+)-H(+)-antiport, a high turnover rate, and the almost exclusive binding selectivity for aldosterone. Dexamethasone, RU 26988, corticosterone, ouabain, amiloride, and 18-hydroxyprogesterone were inactive as ligands. Deoxycorticosterone acetate had an intermediate activity with an apparent Kd of 100 nM. These findings are the first to demonstrate membrane binding of aldosterone being compatible with major aspects of its nongenomic effects.