Effects of dopaminergic blocking agents on distal colon motility.

Four different dopaminergic blocking agents were able to modify the motility of the distal colon: haloperidol, sulpiride, pimozide, and thioridazine. Haloperidol and sulpiride induced different and frequently antagonistic responses; however, the effects induced by these drugs changed depending on the preexisting pattern of motility. Intestinal tone and sigmoidal or rectal phasic activity predominance are the main factors that influence responses. Biperiden, a centrally acting anticholinergic drug, and dihydroergotamine, an antinoradrenergic drug, annulled the rebound of motility induced by sulpiride in high intestinal-tone and low intestinal-tone subjects, respectively. Our results suggest that the dopaminergic system plays a role in the distal colon motility in humans.