Effect of potassium intake on the final steps of aldosterone biosynthesis in the rat. 3. Combined sodium and potassium restriction.

Abstract

ABSTRACT Capsular adrenals ("zona glomerulosa") of rats which had been kept on a sodium- and potassium-deficient diet and which were markedly hypokalaemic, converted tritiated corticosterone to 18-hydroxycorticosterone and aldosterone, and tritiated cortexolone to cortisol at the same respective rates as the capsular adrenals of sodium- and potassium-replete animals. Aldosterone production from endogenous precursors was elevated under basal conditions of incubation, but not under stimulation by added serotonin. Corticosterone and deoxycorticosterone outputs were normal during incubation with or without serotonin. Capsular adrenals of rats which had been kept first on a potassium-deficient diet for two weeks and then on a sodium- and potassium-deficient diet for two weeks converted 18 times more tritiated corticosterone to 18-hydroxycorticosterone and aldosterone and produced 5 times more aldosterone from endogenous precursors than the tissue of rats which had been kept on the potassium-deficient diet for the whole period, although the serum potassium was similarly low in both groups. These results indicate that under simple potassium restriction as well as under combined sodium and potassium restriction, neither the plasma potassium concentration nor the total body potassium is the only regulator of the activity of the enzymes involved in the final steps of aldosterone biosynthesis.