THE INTESTINO-INTESTINAL INHIBITORY REFLEX: THRESHOLD VARIATIONS, SENSITIZATION AND SUMMATION

Abstract

The factors that determine the minimal pressure required to elicit the intestino-intestinal inhibitory reflex have been studied in unanesthetized dogs, by recording the responses of one intestinal segment (Thiry loop) during the disten-tion of another segment (Thiry-Vella loop) with balloons of various lengths and utilizing various pressures. The minimal pressure required to elicit the reflex is lowered as the length of the jejunum distended is increased. The effectiveness of a given pressure in eliciting the reflex is greater as the length of the jejunum distended is increased. These results may be readily explained on the basis of spatial summation in the central nervous system, or in the autonomic ganglia involved. An effective distention of any duration, or a prolonged subthreshold distention. Evidence is presented that this is a peripheral sensitization occurring at the site of distention.