Abstract
This study was designed to investigate gastrointestinal dysfunctions, especially the effects of gastrointestinal prokinetic agents on digestive disorders involving lowered motility. The effects of α2-adrenergic agonists for treating acute abdominal disorders involving intestinal torsion in horses were also investigated. The results are as follows: (1) It appeared that the functions of migrating contractions (MC) in horses were to transfer the contents of the digestive tract as soon as possible to the cecum and colon, in addition to maintaining homeostatis in the digestive tract. (2) Motilin was seen to be involved in the regulation mechanism of intestinal motility in the horse as well as in humans and dogs, and brought about MC. (3) The intravenous injection of cisapride brought about MC in the small intestine. With administration of a higher dose of 0.75 or 1.0 mg/kg, a significant increase (P<0.05) in MC frequency was observed. (4) It was clear that the inhibitory effects of the α2-adrenergic agonists persisted for a longer time with a more remarkable reduction of contractions in the cecum and colon than in the jejunum. When α2-adrenergic agonists are used for relieving intestinal tension, it is recommended that medetomidine is more effective than xylazine.
