Effect of vagotomy on electrical activity of the small intestine of the dog

The effect of bilateral thoracic vagotomy on the myoelectric activity of the small intestine was determined in conscious dogs. Animals were implanted with electrodes spaced 25 cm apart along the serosal surface of the small intestine, and a cannula was placed in the most dependent portion of the stomach. Recordings were made with dogs in the fasted and fed states. Two distinct patterns of myoelectric activity were recorded: one typical of the fasted state (the interdigestive myoelectric complex) and one typical of the fed state. After completion of the control recording periods, a truncal vagotomy was performed on each animal. Completeness of vagotomy was confirmed by lack of a gastric secretory response to insulin. Gastric stasis occurred after vagotomy; therefore, the animals' stomachs were emptied via the gastric cannula to obtain a fasted condition. Vagotomy had little to no effect on the fasted pattern of myoelectric activity. The fed pattern was significantly altered in two of the three animals. This alteration could be due to the effect of vagotomy on gastrin release. We conclude that nervous pathways within the vagus may exert some influence on intestinal myoelectric activity but that other neural-humoral pathways are probably involved.