Effects of dopamine and dopamine antagonists on postprandial release of pancreatic polypeptide in dogs and in healthy volunteers.

The effect of dopamine, 0.006, 0.12, 1.2, and 2.4 mg X kg-1 X h1, and the dopamine antagonist sulpiride on postprandial pancreatic polypeptide (PP) release has been studied in dogs. Dopamine reduced PP release, the reduction ranging between 28% and 97% of the integrated PP response after food. The inhibition obtained with dopamine, 0.12 and 2.4 mg X kg-1 X h-1, could be partly reversed (p less than 0.05) by sulpiride, 7.5 mg X kg-1. The concomitant administration of phentolamine, 1.0 mg X kg-1, and propranolol, 0.5 mg X kg -1, partly reversed the inhibition obtained with dopamine, 2.4 mg X kg-1 X h-1 (p less than 0.05). In healthy volunteers basal PP concentration and postprandial PP release were diminished by dopamine, 0.12 mg X kg-1 X h-1 (p less than 0.02). Sulpiride in dogs and haloperidol in volunteers reduced PP release when given without concomitant administration of dopamine. It is concluded that dopamine inhibits postprandial PP release via both dopaminergic and adrenergic receptors.