Evidence for endogenous dopaminergic control of mineralocorticoids secretion in normal subjects and in patients with hyperaldosteronism.

The role of endogenous dopamine (DA) in the secretion of several mineralocorticoids was studied in six normal subjects, eight patients with primary aldosteronism (PA), two patients with non-familial idiopathic hyperaldosteronism (NF-IHA), and four patients with familial IHA (F-IHA). To these subjects 10 mg metoclopramide (MCP) was administered intravenously, and plasma aldosterone (Ald), 18-OH-corticosterone (18-OH-B), 18-OH-11-deoxycorticosterone (18-OH-DOC), and DOC were measured by RIA. Further, five normal subjects were studied with MCP test after pretreatment with DA infusion (5 micrograms/kg/min over 90 min). After the administration of MCP, normal subjects showed significant increases in their plasma Ald and 18-OH-B, and slight increases in plasma 18-OH-DOC and DOC. However, no significant changes were observed in plasma ACTH, cortisol, PRA, or serum K, Na or Cl. In patients with PA and NF-IHA, plasma Ald and the three precursors were increased after administration of MCP. Especially, marked increases in plasma 18-OH-DOC were seen in PA patients. In contrast, F-IHA patients showed increases in the above mineralocorticoids except 18-OH-B. Following DA infusion in normal subjects neither basal plasma Ald secretion nor the responsivenesses to MCP were modified. These results suggest that endogenous DA plays an inhibitory role in the terminal stages of mineralocorticoids production in man. However, the degrees of the dopaminergic inhibition may be different in normal subjects and the patients with mineralocorticoids excess, and among the three groups of aldosteronism mentioned above.