Dopamine delays gastric emptying and induces retrograde power contractions with enterogastric reflux.

The purpose of the study was to elucidate the effects of dopamine on gastroduodenal motility and gastric emptying of an acaloric viscous meal. In four conscious dogs, antral, pyloric and duodenal contractions were recorded with extraluminal strain gage force transducers and induction coils. Gastric emptying was assessed radiographically. Dopamine at low dose (5 micrograms/kg x min) significantly diminished gastric emptying. It was mainly caused by a reduction in the contraction force of the antral waves. Dopamine at higher dose (10-15 micrograms/kg x min) induced retrograde power contractions accompanied by enterogastric reflux. When the dopamine infusion was stopped after the occurrence of a reverse power contraction, the antrum exhibited forceful contractions but gastric emptying ceased due to a profound decrease in antral tone. The results suggest that dopamine 1) inhibits gastric emptying of viscous meals, 2) induces reverse power contractions independently from vomiting, and that 3) antral tone is a basic requirement for gastric emptying of viscous meals.