Control of intestinal rhythmic contractions by a duodenal pacemaker

Abstract

Rhythmic contractions of the small intestine were recorded in duodenal fistula dogs and in excised dog's intestine. The frequency of contraction showed a stepwise decrease from duodenum to ileum in both intact and excised intestine. Local cooling of a short segment of the upper duodenum caused a significant decrease in frequency of rhythmic contractions throughout the intestine below the cooled area but not above, without significant change in rectal temperature. The frequency of contractions in the excised intestine was 25–30% less than in corresponding areas of intact intestine. The results indicate that influences transmitted from the duodenum, perhaps associated with slow electrical waves, increase the frequency of rhythmic contractions throughout the entire small intestine probably by stimulating the muscle to contract at a frequency in excess of its inherent myogenic rhythm.