Alterations of Aldosterone Biosynthesis by Rat Adrenal Tissue Due to Increased Intake of Sodium and Potassium

Three groups of rats received respectively the following drinking fluids for two weeks: sucrose 5%; NaCl 0.154 m + sucrose; KCl 0.154 m + sucrose. Aldosterone biosynthesis by quartered adrenal glands of these animals was studied under various in vitro conditions. Adrenals from rats drinking sucrose alone produced significantly more aldosterone under all conditions of incubation than adrenals from rats drinking NaCl, which produced more corticosterone and deoxycorticosterone. Tissue from animals drinking NaCl converted less unlabelled progesterone, 11β-hydroxyprogesterone, deoxycorticosterone and corticosterone to aldosterone and incorporated less tritiated pregnenolone, progesterone, deoxycorticosterone and corticosterone into aldosterone. Adrenals from rats drinking KCl produced less aldosterone than adrenals from rats drinking sucrose under basal conditions but not under stimulation by ACTH or potassium ions. In both groups, the production of corticosterone and of deoxycorticosterone was the same under various test conditions. These results indicate that a high sodium intake inactivates one or both enzymes essential for the conversion of corticosterone to aldosterone, whereas a high potassium intake has no significant effect on these later steps of aldosterone biosynthesis.