[Gln4]neurotensin has differential effects on isolated muscle strips of the two muscle layers in the dog ileum. [Gln4]neurotensin stimulates the circular muscle partially through cholinergic nerves at preganglionic sites and partially through a direct myogenic effect. [Gln4]neurotensin inhibits the spontaneous activity of the longitudinal muscle presumably by reducing the excitability of cholinergic nerves at postganglionic sites.