Effects of vagal cryo-interruption on colon contractions in monkeys

The influence of the vagus nerve on normal colon contractions, and the distal extent of this influence along the colon, is unknown. It is generally thought that the vagus nerve has little, if any, influence on normal colon contractions, and if there is any effect, it is limited to the proximal colon. The technique of reversible truncal vagotomy by cooling (vagal cryo-interruption) was used to explore the influence, and extent of any influence, of the vagus nerve on contractions of the colon in unanesthetized monkeys. Each monkey was subjected to vagal cryo-interruption in the fasted and fed states. In both states this caused a significant decrease in contractions in the proximal, middle, and distal portions of the colon, compared with baseline control and recovery periods. These studies indicate that the vagus nerve plays a role in normal contractions of the intra-abdominal colon in both the fasted and the fed states and that it also plays a role in the gastrocolic response.