An experimental study of the diurnal changes in colonic motility centering on defecation.

The following findings have been obtained as a result of making an assessment regarding the diurnal changes in colonic motility by means of continuous measurement of contractile waves by using strain gauge force transducers and roentgenographic observation in conscious dogs. 1. Before defecation, the contractile force of the wave was weak, frequency of its emergence was also small, and transfer of intestinal content was slow, showing decrease of colonic motility. 2. After defecation, the gradually increasing and decreasing contractile wave groups became clear, and the contractile force was intensified concurrently with increase of its emerging frequency. Transfer of intestinal content to the anal side was rapid, and recovery of colonic motility was observed. 3. The recovery of the colonic motility after defecation was observed regardless of digestive or interdigestive state. 4. By intake of food, increase of the colonic motility corresponding to gastrocolic response was observed, but it was due to the increase of emerging frequency of contractile wave, for which no change was observed in contractile force or duration in each individual waves. 5. It was suggested that the contractile motion which undergoes gradual increase and decrease is the basic pattern in the colonic motility and that the colonic motility changes by the differences of amount, shape and hardness of intestinal content, and decreases gradually along with increase of intestinal content, but the basic pattern of contractile motion is restored by inflow of intestinal content into the colon which became empty after defecation. From the above it was considered to be inadequate to use the pattern classification of digestive and interdigestive state for the analysis of colonic motility and that assessments should be made centering on defecation.