Adrenocorticotropin-mediated effect of metoclopramide on plasma aldosterone in man.
Five healthy adult men were given metoclopramide (10 and 20 mg) iv and the effects of L-dopa and dexamethasone on metoclopramide-induced increases in plasma aldosterone concentration were determined. Plasma PRL, ACTH, and cortisol levels were also measured and the results reported in a previous study. After an injection of 10 mg metoclopramide, aldosterone levels increased significantly. The aldosterone rise was inhibited by L-dopa, but not by dexamethasone. After injecting 20 mg metoclopramide, aldosterone levels increased significantly vs. both the control and the basal level. The aldosterone increase was not inhibited by L-dopa pretreatment, whereas pretreatment with dexamethasone did suppress it. The data suggest that metoclopramide increased aldosterone secretion through an ACTH-dependent (stress mediated) effect in addition to its antidopaminergic adrenal action, simultaneously. There were no significant differences between the ACTH-dependent and dopamine antagonist-mediated aldosterone increases in either the 10- or 20-mg tests. However, the ACTH-dependent aldosterone increase was statistically greater in the 20-mg test than in the 10-mg test, whereas there was only a slight and not statistically significant difference in the dopamine antagonist-mediated aldosterone increase between the tests. This means that the ACTH-dependent component of the aldosterone secretion is affected by the doubling of the metoclopramide dose, whereas the dopamine antagonist-mediated component is not.
D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000328:Adult; D000450:Aldosterone / Q000097:blood*; D003907:Dexamethasone; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007700:Kinetics; D007980:Levodopa; D008297:Male; D008787:Metoclopramide / Q000494:pharmacology*; D013312:Stress, Physiological / Q000097:blood
D007980:Levodopa; D000450:Aldosterone; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D008787:Metoclopramide