Colonic giant migrating contractions induced by glycerol enema in anesthetized rats.

Colonic motility was measured with three catheter pressure transducers that were inserted into the descending colon at the distance of 4 cm, 6 cm and 8 cm from the anal verge in anesthetized rats. Colonic infusion of glycerol (65%, 2 ml/kg) induced large phasic pressure changes with high amplitude and long duration. Some of the pressure changes propagated over all the three recording sites, appearing to be equivalent to giant migrating contractions. These glycerol-induced large propulsions were abolished by lidocaine (5%, 2 ml/kg, intracolon), hexamethonium (10 mg/kg, i.v.) or clonidine (30 micrograms/kg, i.v.); and they were almost entirely suppressed by atropine (3 mg/kg, i.v.), suggesting the principal involvement of the cholinergic neural pathway.