Modification of electrical field stimulation-induced contractions in the guinea-pig ileum by metoclopramide and ICS 205-930 depends on the integrity of the mucosa.

Contractions induced by electrical field stimulation of guinea-pig ileum longitudinal muscle strips were enhanced by metoclopramide and ICS 205-930 at concentrations similar to those required to antagonize at 5-hydroxytryptamine 'M' receptors. The enhancement of contraction was observed in intact ileum strips but was not recorded in the longitudinal muscle myenteric plexus preparation or from the ileum with the mucosal layer removed. It is concluded that an intact mucosal layer is required for metoclopramide and ICS 205-930 to enhance electrical field stimulation-induced contractions of the guinea-pig ileum.