Intraluminal pressure of the small intestine of the unanesthetized dog

Intraluminal pressure recordings have been performed in 14 unanesthetized dogs via a Mann-Bollman fistula by means of an air-filled balloon catheter system and a water-filled catheter system. The dynamic response is adequate for studying intraluminal pressures of the small intestine. Resting pressures in the proximal, middle and distal jejunum averaged approximately 6 mm Hg above atmosphere and no appreciable differences were noted between the different areas. The contraction time of simple, monophasic waves was fairly constant (approximately 1.0 s in duration) and usually unrelated to amplitude of the wave. Propulsion of intraluminal contents occurred in the absence of complex (type III) waves. A pressure wave in a proximal segment of jejunum was temporally related to a wave occurring 5 cm distally. The mean intervals between the proximal and distal contractions were: 0.42 s in the proximal jejunum; 0.74 s in the middle jejunum; 1.56 s in the distal jejunum; 2.79 s in the ileum. These time lags have a log normal distribution. The length of the physiologic segment in the jejunum of the dog varied from 1.0-8.0 cm and was usually 2-4 cm.