Dopamine 3-sulfate inhibits aldosterone secretion in cultured bovine adrenal cells

It has been demonstrated that dopamine inhibits the aldosterone (Aldo) secretion in bovine adrenal cells in vitro. Because the majority of the total circulating dopamine (DA) in bovine plasma (72%) is present in sulfoconjugated form (6.8 +/- 3.4 pmol/ml) and free DA, DA sulfate, and phenolsulfotransferase (PST) activity can be found in the bovine adrenal cortex, we examined whether the inhibitory action of free DA on angiotensin II- (ANG II) stimulated Aldo secretion by cultured bovine adrenal cells can also be reproduced by sulfoconjugated DA analogues. Cells from the bovine adrenal glands cultured for 3 days before testing responded to 10(-8) M ANG II stimulation by a 10- to 12-fold increase in Aldo output. This stimulatory effect was partially inhibited by the addition of free DA and DA 3-sulfate, whereas DA 4-sulfate was inactive. Both free DA and DA 3-sulfate produced their maximal inhibitory effect at a concentration of 100 microM, with a decrease in Aldo secretion by 61% (free DA) and 44% (DA 3-sulfate). The slightly different inhibition curves for DA and for DA 3-sulfate on Aldo secretion cannot be explained by liberation of free DA through hydrolytic processes because less than 1% free DA was detected after the incubation of the cells with sulfoconjugated DA. These in vitro findings suggest that DA 3-sulfate may be effective in complementing the dopaminergic inhibition of Aldo secretion at the adrenal level.