A study of aldosterone-binding components of rat kidney

Abstract

We have confirmed that aldosterone binds to macro-molecular receptors in the nuclear and cytosol fractions of rat kidney in vivo and in vitro. A lesser degree of aldosterone binding in vitro is apparent in fractions of heart, liver, and blood; no differences in binding to kidney components were apparent in male and female animals. -- Binding to kidney components appears unstable even at 0ﾟ; some stabilization is offered by the presence of aldosterone or 20% glycerol. Aldosterone-macromolecular complexes formed in vivo are susceptible to dissociation by temperature increases above 0ﾟ and by pH extremes, but not by hyaluronidase. In vitro studies show that p-HMB inhibits complex formation and that aldosterone does not protect against such inhibition. -- The binding of aldosterone to kidney components is greater in adrenalectomized animals than in unoperated controls and this increase in binding is apparent at 1 - 2 hours after surgery. -- Attempts at purification of aldosterone-binding components by Sephadex chromatography and on sucrose density gradients were unsuccessful. -- Kidney appears to contain at least two components which bind aldosterone: -- (a) a relatively stable, specific component with a low affinity for aldosterone, and (b) an unstable, less specific component whose affinity for aldosterone has not been determined.