Direct<i>β</i>-Adrenergic Stimulation of Aldosterone Secretion in Cultured Bovine Adrenal Subcapsular Cells*

TLDR

The study investigates direct catecholamine effects on aldosterone secretion in cultured bovine adrenal subcapsular cells and evaluates the physiological relevance of β‑adrenergic stimulation. Bovine adrenal subcapsular cells were dispersed with collagenase and DNAse, cultured at high density (1.5–2 × 10⁶ cells/mL) for three days, and displayed high sensitivity to angiotensin II and ACTH (ED₆₀ ≈ 1.4–1.5 nm). Adrenergic agonists produced 4–6‑fold aldosterone stimulation, with (−)isoproterenol most potent; β‑adrenergic antagonists (alprenolol, ICI 118.551, atenolol) strongly inhibited this effect, while α‑antagonists had weak impact, and phosphodiesterase inhibition doubled the maximal response, indicating a β1‑adrenergic, cAMP‑mediated mechanism. Endocrinology 115: 485–492, 1984.

Abstract

Primary culture of bovine adrenal subcapsular cells was used to investigate direct effects of catecholamines on aldosterone secretion. Cells dispersed with collagenase and DNAse and cultured at high density (1.5–2 million/ml) for 3 days displayed high sensitivity to angiotensin II and ACTH, with an ED60 of 1.4 and 1.5 nm, respectively. Adrenergic agonists elicited a 4- to 6-fold stimulation of aldosterone secretion with potency order (−)isoproterenol greater than (−)epinephrine equals (−)norepinephrine greater than (+)isoproterenol, and corresponding ED50 5, 240, 213, and 3000 nm, respectively. No reproducible inhibition by dopamine of basal or stimulated levels of aldosterone secretion could be detected, but a weak stimulatory effect was sometimes observed at high concentration greater than 10 μM. (−)Isoproterenol stimulation of aldosterone production was potently inhibited by the β-adrenergic antagonists (−)alprenolol and (+)alprenolol with potencies of 1.8 and 110 nm, respectively. The α-adrenergic antagonists prazosin, yohimbine, and phentolamine only weakly inhibited (−)isoproterenol stimulation with potencies of 5, 13, and 140 μm, respectively. The potent β2-adrenergic antagonist ICI 118.551 and the weaker β1-adrenergic antagonist atenolol were roughly equipotent with potencies of 0.27 and 0.44 μm, respectively. Addition of the phosphodiesterase inhibitor Ro 20-1724 at 10 nm doubled the maximum stimulation effect of (−)isoproterenol without changing the potency of the catecholamine or the basal level of aldosterone secretion, suggesting a potential role of cAMP as a mediator of isoproterenol stimulation. These results indicate the presence of a β1-adrenergic receptor stimulating aldosterone secretion in bovine zona glomerulosa cells. The physiological significance of direct β-adrenergic stimulation of aldosterone production is currently being assessed. (Endocrinology115: 485–492, 1984)