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 gastri c tone and whether the effects of dopamine can be blocked by a dopamine ant agonist. Methods: Eight healthy male volunteers were studied on two occasions in a r andomized 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 milligram s of the dopamine-antagonist metoclopramid was given before the dopamine in fusion on one occasion and during the dopamine infusion (7.5 mu g kg(-1) mi n(-1)) on the other occasion. The gastric tone was measured by an electroni c barostat, an instrument with an electronic control system that maintains a constant preset pressure within an air-filled, flaccid intragastric bag b y means of momentary changes in the intragastric volume of air. Volume and pressure in the gastric bag were continuously recorded by the electronic ba rostat and sampled in a computer. Results: Dopamine induced a dose-related increase in the intragastric bag v olume, Metoclopramid given as a 10 mg i.v. bolus dose during the infusion o f dopamine significantly decreased the intragastric bag volume, but 10 mg o f 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.