The Colonic-Jejunal Reflex in the Dog. ∗

Abstract

In a study of the influence of treadmill running on jejunal Thiry fistula motility in the dog, variable results were secured. Thus at times there was complete inhibition of motility and reduced tone during the running, whereas at other times the motility was little modified. Chance observations, on several occasions, associated balking, attempts to sit down, and defecations while running with reduced jejunal tone and motility. The plausibility of the notion that all of these “misbehaviors” might be expressions of the defecatory reflex and thus have an ultimate seat in colonic activity and that this might help to untangle the mechanism by which exercise operates on the jejunum, led us to investigate more specifically into the influence of colonic stimulation on the jejunal motility and tone. Two approaches appeared obvious: 1. To observe the jejunal motility when the colon is expressly stimulated as by distension. 2. To observe simultaneously the spontaneous activity of jejunum and colon at rest and during exercise to determine the interactions resulting from peristalsis, etc., originating in either.

The latter approach, which appears to lead to disclosure of the more natural conditions, is a tedious one and our data is accumulating slowly. The first approach has led us into a field where King 1 has already done careful work. Pearcy and Van Liere 2 and Pearcy and Weaver, 3 working on animals under anesthesia or after decerebration, have also reported several relevant findings.