Metoclopramide Enhances Bethanechol‐induced Pancreatic Exocrine Secretion of the Dog

Abstract

The effects of metoclopramide on pancreatic exocrine secretion were investigated in the pentobarbitone-anaesthetized dog. All drugs were injected into the femoral vein. Metoclopramide (10-1000 micrograms/kg) did not change the resting rate of pancreatic secretion. Pancreatic secretion, induced by bethanechol (3 micrograms/kg), was dose-dependently enhanced by simultaneous injections of metoclopramide (10 and 30 micrograms/kg), but the protein and bicarbonate concentrations of the pancreatic juice were not affected. Secretions induced by secretin (0.1 units/kg) and dopamine (3 micrograms/kg) were not modified by metoclopramide at up to 30 micrograms/kg. A larger dose of metoclopramide (1000 micrograms/kg) suppressed dopamine-induced secretion to a lesser extent than the same dose of sulpiride. From these results, it is concluded that metoclopramide enhances secretory responses to cholinergic stimulations by peripherally sensitizing the muscarinic receptor-mediated exocrine process and this drug is a weaker antagonist of the dopamine D2 receptors than sulpiride.

Atypical antipsychotics – effects of amisulpride on salivary secretion and on clozapine‐induced sialorrhea

“…Interestingly, the D2/D3‐dopamine receptor antagonists – sulpiride, in humans, and metoclopramide, in dogs – are reported to enhance the pancreatic exocrine secretion evoked by infusions of secretin and cholecystokinin and of bethanechol, respectively (Gullo et al , 1980; Yamagishi et al , 1985). The removal of an inhibitory influence of dopamine on the pancreatic secretion was considered as one explanation of the potentiating phenomenon.…”