MOVEMENTS OF THE SMALL INTESTINE IN TRANSPORT OF INTRALUMNAL CONTENTS

Abstract

In order to study the movements of the small intestine during transport of solid or fluid materials, the mechanogram, action potentials of the intestinal muscle and the outflow volume of perfusion fluid are recorded on the denervated jejunal loop in the dog anesthetized with urethan and morphine.1. When the bolus is inserted into the loop, the intestinal movements are abolished over 14cm anal to the bolus: The spike potentials decrease in number and amplitude or disappear completely, these responses continue until the bolus arrives at the recording point. On the other hand, the movements at the region oral to the bolus are accelerated remarkably, and the bolus is transported gradually anad on account of these. When the bolus reaches the recording point, the spike potentials are discharged continuously on the summated slow potentials over ten seconds and followed by the rhythmic discharges of the spike potentials are increased in rate with increase of the spike potentials in number.2. Since the excitation above and the inhibition below the bolus described above are abolished after applying 0.1% cocaine solution to the lumen to anesthetize the mucosa, it may be concluded that these responses are produced by the intrinsic mucosal reflex.The movements below the bolus are accelerated in a few cases. It shows that the strong contraction waves produced above the bolus propagate to the anal side predominating over the inhibitory state below the bolus.3. When the loop is perfused with the saline solution under the intraluminal pressure of about 10cm H2O, one descending wave produces one outflow of the fluid.When the saline solution is replaced by N/40 HCl-solution, the slow potentials are increased in rate, accompanying increase of the spike potentials in number and the lumen grows narrow, with consequent, remarkable decrease in the outflow volume.4. From these results it may be concluded that the intrinsic reflexes, especially the intrinsic mucosal reflex, play an important role in the transport of solid and fluid.The author is indebted to Prof.T.HUKUHARA for his advice and criticism.