Gastrointestinal myoelectric activity was investigated in conscious rabbits with chronically implanted electrodes. As rabbit stomach is never empty, food was removed 1 h before the beginning of recordings. Propagated activity fronts spontaneously started in the jejunum without associated changes in the antroduodenal area. Intravenous administration of either motilin (600-1500 ng/kg) or erythromycin (5-50 micrograms/kg) did not modify antral activity, but simultaneously increased duodenal and jejunal activity in a dose-dependent manner. Spontaneous and induced jejunal activity fronts showed some similarities. However, those induced did not propagate and were not followed by a quiescence period. The effects of motilin (900 ng/kg) and erythromycin (25 micrograms/kg) were resistant to atropine (0.5 mg/kg), hexamethonium (2 mg/kg), or ondansetron (0.5 mg/kg). These results suggest that motilin is not a physiological modulator of the migrating myoelectric complex (MMC) in rabbits. Moreover, neither cholinergic nor 5-HT3 receptors are involved in either motilin or erythromycin-induced actions.