Dopamine reduces gastric tone in a dose-related manner

Background: Dopamine may have effects on gastrointestinal motility. The aim of this study was, therefore, to determine whether dopamine reduces gastric tone and whether the effects of dopamine can be blocked by a dopamine antagonist. Methods: Eight healthy male volunteers were studied on two occasions in a randomized order. A continuous infusion of incremental doses of dopamine (2.5, 5.0, 7.5 mu g kg(-1) min(-1)) was given on both occasions. Ten milligrams of the dopamine-antagonist metoclopramid was given before the dopamine infusion on one occasion and during the dopamine infusion (7.5 mu g kg(-1) min(-1)) on the other occasion. The gastric tone was measured by an electronic barostat, an instrument with an electronic control system that maintains a constant preset pressure within an air-filled, flaccid intragastric bag by means of momentary changes in the intragastric volume of air. Volume and pressure in the gastric bag were continuously recorded by the electronic barostat and sampled in a computer. Results: Dopamine induced a dose-related increase in the intragastric bag volume, Metoclopramid given as a 10 mg i.v. bolus dose during the infusion of dopamine significantly decreased the intragastric bag volume, but 10 mg of metoclopramid i.v. before the dopamine infusion did not influence the bag volume per se. Conclusion: Dopamine decreases gastric tone in a dose-related manner and 10 mg of the dopamine-antagonist metoclopramid is not enough to fully reverse these effects.