Inhibitory effects of dopamine and isoprenaline on antral motor activity stimulated by acetylcholine or physostigmine in vitro.

Continuous pressure recordings were made in guinea-pig antral pouches in vitro. The antral phasic activity was stimulated by acetylcholine and by the cholinesterase inhibitory agent physostigmine. Dopamine and isoprenaline both significantly impaired antral pressure responses to physostigmine, whereas the acetylcholine-induced response was not significantly reduced. This suggests that both dopamine and isoprenaline to some extent act by reducing the spontaneously released acetylcholine, suggesting that both drugs act on intramural cholinergic neural pathways.