Effect of duodenal cooling on small intestinal pacing.

The aim of this study was to determine whether mid-duodenal cooling would decrease the frequency of the pacesetter potentials in the distal duodenum and so facilitate pacing of the distal duodenum by electrical stimuli. Stepwise cooling of the mid duodenum of four awake dogs from 38 degrees to 4 degrees C decreased markedly the frequency of the distal duodenal pacesetter potentials (mean +/- SEM, 19.7 +/- 0.6 versus 13.6 +/- 0.4 cycles/min, P less than 0.05). Moreover, during cooling, electrical pacing near the ligament of Treitz increased the frequency of the pacesetter potentials in the distal duodenum and reversed their direction of travel from caudad to orad. The maximum driven frequency was progressively slowed as the mid duodenum was cooled from 38 degrees to 4 degrees C (20.9 +/- 0.5 versus 18.0 +/- 0.7 cycles/min, P less than 0.05). Because the unpaced frequency declined more rapidly than the maximum driven frequency as the mid duodenum was cooled, the spread between them, or the "pacing range," enlarged with decreasing temperature. We concluded that duodenal cooling decreased the frequency of the distal duodenal pacesetter potentials and expanded the range over which the pacesetter potentials could be paced.