Bradykinin stimulates aldosterone release from cultured bovine adrenocortical cells through bradykinin B2 receptors.

The adrenal cortex contains a kallikrein-like enzyme that may lead to bradykinin (BK) formation. This study was designed to determine whether BK acts on adrenocortical cells to stimulate steroid secretion. BK, Lys-BK, a specific BK 2 (B2) receptor agonist, and desArg9-BK, a specific BK 1 (B1) receptor agonist, all stimulated aldosterone secretion from cultured bovine adrenal zona glomerulosa cells. BK and Lys-BK were equipotent (EC50 = 2 x 10(-9) M), whereas desArg9-BK was 1000-fold less potent. The maximal effects of BK and BK analogs were comparable to the maximal effects of adrenocorticotropin or angiotensin II. A B2, but not a B1, receptor antagonist inhibited BK-stimulated aldosterone release. Verapamil and N,N-diethylamino-octyl-3,4,5-trimethoxybenzoate, which reduce intracellular calcium concentrations, reduced BK-stimulated aldosterone secretion. Although BK stimulated both prostacyclin and aldosterone production, indomethacin abolished prostacyclin production without affecting aldosterone secretion. In cultured adrenal fasciculata cells, high concentrations of BK stimulated cortisol release, but B1 or B2 receptor agonists were not effective. BK-stimulated cortisol secretion was reduced by N,N-diethylamino-octyl-3,4,5-trimethoxybenzoate but not by indomethacin. In summary, BK stimulates aldosterone release from cultured adrenal glomerulosa cells via high affinity B2 receptors. The effect is calcium-dependent and independent of prostaglandins. BK also increases cortisol release; however, this stimulation requires high concentrations of BK and may be mediated by an unknown receptor or by a receptor-independent mechanism.