INDOMETHACIN-INDUCED LESION MODIFIES CONTRACTILE ACTIVITY IN RAT SMALL-INTESTINES

Background: Indomethacin induces intestinal lesions. The change in con tractility of segments with lesions was studied. Methods: Motility was recorded in segments with lesions isolated from the rat small intesti ne 24 h after a subcutaneous injection of indomethacin (20 mg/kg). Res ults: Concentration-contraction curves for acetylcholine shifted leftw ard independently of the degree of severity of lesions, but the curves for carbachol and 5-hydroxytryptamine did not. Contractions produced by intramural nerve stimulation were enhanced in segments with no visi ble damage but decreased with progression of lesions. Neostigmine augm ented them in normal rats but not in indomethacin-treated rats. The pe ristaltic activity was enhanced in segments with no visible lesions. C onclusions: The results suggest that treatment of the rat with indomet hacin enhances contractility of the small intestine owing to diminutio n of acetylcholinesterase activity independently of the degree of lesi ons and reduces it owing to decreased responsiveness of enteric neuron s with the progression of lesions.