Effects of bombesin on neurotransmission in cat duodenal smooth muscle

The effects of tetradecapeptide bombesin on contractile activity and field electrical stimulation (FES) evoked contractions of duodenal smooth muscle were studied. Bombesin produced an increase in the tone as well as the amplitude and frequency of the spontaneous contractions. The atropine-sensitive contraction and nonadrenergic noncholinergic relaxation in responses to FES which were tetrodotoxin-sensitive significantly increased in amplitude after bombesin. This suggests that bombesin not only provokes release of acethylcholine but can also modulate the release of noncholinergic nonadrenergic neurotransmitter in the enteric nervous system.