Bradykinin releases acetylcholine from myenteric plexus by a prostaglandin-mediated mechanism.

Release of [3H]acetylcholine (ACh) under the influence of bradykinin was measured from myenteric plexus-longitudinal muscle strips taken from guinea pig small intestine. Bradykinin stimulated the efflux of [3H]ACh in a dose-dependent manner. This stimulation by bradykinin was resistant to the effect of [Des-Arg9-Leu8]-bradykinin but not to indomethacin, indicating that the ACh-releasing action of bradykinin was mediated indirectly by a prostaglandin mechanism. Direct evidence for a stimulation of ACh release by prostaglandin E1 was obtained. Prostaglandin was able to stimulate ACh release in a dose-related fashion. The inhibition of bradykinin-induced ACh release by indomethacin was partly reversed by exogenous prostaglandin E1. These results suggest a neuromodulatory role for bradykinin in the enteric nervous system.