if acetylcholine ach binds to muscarinic receptors in the gi tract, its action is: question 11 options: inhibitory and it causes contraction of smooth muscles and sphincters in the gi tract stimulatory and it causes contraction of smooth muscles and sphincters in the gi tract it is neither stimulatory nor inhibitory because acetylcholine ach does not bind to muscarinic receptors. it binds to alpha 1 and beta 1 receptors. inhibitory and it causes relaxation of smooth muscles and sphincters in the gi tract