Loci of Action of Regulators of Aldosterone Biosynthesis in Isolated Glomerulosa Cells

TLDR: The effects of angiotensin II (All), ACTH, and potassium on early and late steps of aldosterone biosynthesis were studied in collagenase-dispersed cells from rat adrenal capsules and dog zona glomerulosa to measure the formation of pregnenolone and later steps of biosynthetic conversion in the absence of endogenous precursors.

Abstract: The effects of angiotensin II (All), ACTH, and potassium on early and late steps of aldosterone biosynthesis were studied in collagenase-dispersed cells from rat adrenal capsules and dog zona glomerulosa. Isolated cells were incubated with a cyanoketone derivative (WIN 19,578) to isolate the nearly and late portions of the biosynthetic pathway. In this way, the formation of pregnenolone and later steps of biosynthetic conversion in the absence of endogenous precursors could be measured independently during stimulation by the three regulators. During incubation for 3 h with 10 nM All, 10 nM ACTH, or 15 mM potassium, marked stimulation of pregnenolone production was observed in glomerulosa cells of both species. In rat glomerulosa cells, each of the three regulators also stimulated conversion of exogenous corticosterone to aldosterone. In dog glomerulosa cells, All and potassium, but not ACTH, stimulated the conversion of corticosterone to aldosterone. In rat glomerulosa cells, aldosterone production from e...