Role of muscarinic receptor subtypes in the regulation of migrating myoelectric complex in the dog

Abstract The role played by muscarinic receptor subtypes in the regulation of the migrating myoelectric complex was investigated in 7 dogs chronically implanted with bipolar electrodes along the small intestine. Pirenzepine (3–300 μg/kg i.v.) and atropine (1–30 μg/kg i.v.) were used as selective and unselective antagonist, respectively. Atropine (30 μg/kg) significantly delayed the onset of the next complex. On the contrary, pirenzepine displayed a biphasic action: low doses ( 1 muscarinic receptor subtype; on the other hand, M 2 receptor activation is needed for the onset of the activity front. Finally, both receptor subtypes determine the normal migration of phase III.