Effect of feeding on the pattern of small bowel transit in the rat

The effect of feeding on the small bowel transit pattern was studied in rats provided with a central venous catheter and a permanent gastric catheter. Solutions of glucose, amino acids or lipids were administered via the gastric catheter for 20 minutes (2 or 10 ml X h-1), while 99Tcm-Solco-HIDA, a bile-excreted radiopharmaceutic, was infused intravenously for 1, 3 or 5 hours. At the end of the intravenous infusion, the gastrointestinal tract was excised and the radioactivity along the specimen was measured. In rats given no gastric feeding, the transit of small bowel contents occurred in well separated portions and the gut segments between the portions were free from radioactivity. With gastric feeding at the higher rate, examination of the small bowel contents after 1 hour showed continuous distribution along the gut, without apparent peaks or empty regions. When examined at 3 and at 5 hours, the small bowel seemed to have resumed its interdigestive pattern. The transit of chyme in the early postprandial period thus occurs in a manner distinctly different from the interdigestive transit pattern. The observations agree closely with electromyographic studies showing postprandial elimination of cyclic recurring activity.