KW-5092 ((1-[2-[[[5-(piperidinomethyl)-2-furanyl]methyl]amino]ethyl]-2- imidazolidinylidene) propanedinitrile fumarate) is a novel gastroprokinetic agent with acetylcholinesterase (AChE) inhibitory activity. The present study examined the effects of KW-5092 on intestinal contraction and on acetylcholine (ACh) release in the isolated longitudinal muscle-myenteric plexus preparation of guinea pig ileum. In the electrically stimulated preparation, KW-5092 enhanced the contraction at 10(-9) M to 3 x 10(-6) M and potentiated the ACh release at 10(-8) M to 3 x 10(-6) M. In the unstimulated preparation, KW-5092 at 10(-8) M to 10(-4) M evoked the contraction and ACh release. Both the contraction and the ACh release by KW-5092 were abolished by tetrodotoxin (10(-7) M) or removal of external Ca2+, and the evoked contraction was abolished by atropine (10(-7) M). The ACh release by KW-5092 was not affected by hexamethonium (3 x 10(-5) M), suggesting that the nicotinic receptor is not involved in the ACh release. Neostigmine, whose AChE inhibitory activity is equipotent to that of KW-5092, did not evoke ACh release even at 3 x 10(-6) M, indicating that the ACh release by KW-5092 is not due to its AChE inhibitory activity. The present results suggest that KW-5092 evokes ACh release by stimulating a cholinergic pathway and that the ACh release by KW-5092 may contribute to its gastroprokinetic effects.