Effect of Dietary Fiber on Intraluminal Pressure and Myoelectrical Activity of Left Colon in Monkeys

The effects of varying intake of dietary fiber content on left colon intraluminal pressure, electrical spike discharge activity, and contractions of circular muscle were measured in stump-tailed monkeys. Animals were preconditioned to sit in restraint chairs and then had the sigmoid colon instrumented with an extraluminal strain gage force transducer, a bipolar serosal electrode and a Thomas cannula to provide access for determining luminal pressure with a perfused, open-tip catheter. Diets containing 0, 5, 10, 15, and 20 g of dietary fiber daily were fed in varying sequences for periods of 3 wk. Observations were made twice during the last week of each diet. Fecal weight increased in animals on a high fiber diet, but changing dietary fiber content did not alter the duration of spike discharge activity and produced only a minimal change in the contraciton frequency of colon circular muscle. Colon intraluminal pressure was increased significantly by feeding low-fiber diets, but intraluminal pressure responses did not always correlate with the myoelectrical activity of the colon circular muscle.