The effects of potassium on early and late steps in aldosterone biosynthesis in cells of the zona glomerulosa.

Abstract

It has been clearly established that potassium can modulate aldosterone biosynthesis. However, the site of action of potassium on the aldosterone biosynthetic pathway has not been definitively established. This study was designed to examine in vitro the effects of potassium on the isolated early phase and the isolated late phase of aldosterone biosynthesis in adrenal cell suspensions. When the potassium concentration was increased in glomerulosa cell suspensions from 0 to 6 mEq/liter, a significant increase in aldosterone production occurred (P < 0.01). However, when the potassium concentration was increased from 6 to 12 mEq/liter, changes observed in aldosterone production were small and inconsistent. The early phase of aldosterone biosynthesis was then isolated, using trilostane to inhibit the conversion of pregnenolone to progesterone and, therefore, to aldosterone. Increasing the potassium concentration of trilostane- treated glomerulosa cell suspensions either from 0 to 6 mEq/liter or from 6 to 12 mE...