Effect of neostigmine on metoclopramide-induced aldosterone secretion in man

This study examines the role of a neostigmine-induced increase in acetylcholine on the aldosterone stimulating effect of metoclopramide. Six normal male volunteers received the following three treatments in a cross-over randomized sequence: neostigmine, 0.5 mg s.c.; metoclopramide 10 mg i.v.; and neostigmine 0.5 mg s.c., followed by metoclopramide 10 mg i.v. Metoclopramide increased serum aldosterone significantly to 161% of basal level at 15 min. With neostigmine aldosterone levels peaked (129%) significantly at 30 min. In the presence of neostigmine, however, the metoclopramide-induced aldosterone response was blunted significantly. These results would suggest that presynaptic autoreceptors depresses the continued output of acetylcholine, thereby blunting the aldosterone responses to metoclopramide significantly.