Aldosterone receptor measurements during changes in dietary sodium.

Type I aldosterone receptors were measured in rat kidney cytosol preparations after alterations in dietary sodium and aldosterone injection. Changes in sodium intake had no effect on receptor number or affinity in adrenalectomized rats. Intact rats had decreased receptor numbers after a low sodium diet compared to those after a high sodium diet (P less than 0.005), and the decrease in receptor number was significantly correlated with the corresponding rise in serum aldosterone (r = -0.65; P less than 0.01). In adrenalectomized rats, injection of aldosterone was associated with a decrease in receptor number, and serum aldosterone correlated inversely with receptor number (r = 0.64; P less than 0.01). We conclude that increases in serum aldosterone decrease the number of available cytoplasmic aldosterone receptors, but changes in sodium intake have no direct effect upon aldosterone receptor number or affinity.