[The participation of met-enkephalin in the display of contractile reactions of the large intestine and ileocecal sphincter].

Blockade of H-cholinoreceptors, alpha- and beta-adrenoreceptors did not lead to disappearance of the colon and ileocecal sphincter contractile responses to i.a. administration of met-enkephalin (0.05-8.0 micrograms). The responses of the colon, as well as ileum and jejunum were augmented under blockade of alpha-adrenoreceptors whereas the responses of ileocecal sphincter decreased. The latters were augmented under blockade of beta-adrenoreceptors. Met-enkephalin infused into the vascular bed of an isolated portion of the intestine (0.01-5.0 micrograms/ml/min), potentiated the colon and ileocecal sphincter responses to acetylcholine (1.0-20.0 micrograms), the colon responses to stimulation of the n. vagus efferent fibers, and the ileocecal sphincter responses to serotonin (20-100 micrograms).