THE EXPERIMENTAL REVERSAL OF INTESTINAL GRADIENTS

Abstract

When considerable injury was produced in the tissues about the ileocecal sphincter of rabbits, they suffered from diarrhea and the colon was emptiea. The ileum was emptied orad and food residues were held back in the duodenum. Peristaltic rushes were few; they were hard to start, and they were slowed and stopped in the lower part of the bowel. After the injury the whole bowel was unusually sensitive to faradic stimuli, and inmost of the experiments the normal gradient in irritability form duodenum to ileum was reversed. With the increased irritability of the bowel the latent periods were shortened, and the fact that this change was more marked in the lower part of the ileum than in the duodenum caused the normal gradient (of latent period) to be flattened. Segments of gut excised from the injured animals and placed in warm aerated Locke''s solution behaved normally, showing that the failure of the bowel to pass onward its contents was not due to injury to the muscle. Chemical injury of the ileocecal region in animals with vagi and splanchnics cut and a large part of the conducting system in the bowel degen- erated, still produced back-pressure in the small bowel and a marked slowing of rush waves. This suggests that the flattening of gradients had something to do with the failure of conduction. Alvarez'' law appears to be confirmed; namely, that irritation at any point in the bowel tends to slow the progress of material coming from the stomach toward it, and to hasten the progress of material moving caudad away from it. The gradient theory of peristalsis appears to be strengthened.