Anatomic features and radiographic observations of gastric emptying and small intestinal motility in the rat.

This study presents the first report of the identification of anatomic structures on survey radiographs of the abdomen of the rat, along with detailed barium contrast studies of the gastrointestinal tract in normal rats. The rats (49 to 112 days old) were chemically restrained with a combination of 0.71 mg ketamine hydrochloride/g of body weight and 0.5 mg of acetylpromazine maleate injected intramuscularly. Following sedation, a 36% (wt/vol) micropulverized barium sulfate suspension was administered via a stomach tube at a dose of 0.02 ml/g of body weight. The radiographic features of the gastrointestinal tract were enhanced after coating of the mucosal surfaces with the high-density barium suspension. Internal structures of the stomach and mucosal surfaces of the intestine were clearly identified. The barium contrast study was used to establish gastrointestinal transit times. The mean gastric emptying time was 11 +/- 4.27 (SEM) min and mean intestinal transit time was 5 +/- 0.75 (SEM) h. Image intensification fluoroscopy was used to observe patterns of small intestinal motility and to establish small intestinal contraction rates. Prominent cluster of circular contractions were primarily observed in the jejunum, and wave-type peristalsis was primarily observed in the duodenum. Isolated circular contractions and weak segmentation patterns were observed in the ileum. The mean contraction rate per minute was observed to be 14 +/- 2.12 (SEM) in the jejunum. We propose that under the conditions of the current study, radiographic investigation of gastrointestinal function in rats is a feasible and inexpensive procedure.