Effect of the Normal Microbial Flora on Gastrointestinal Motility.

The rate of propulsion of gastrointestinal contents was compared in germfree and conventional mice using a non-absorbable radioactive substance, yttrium 91. Following intragastric administration, the marker was propelled much more rapidly through the gastrointestinal tract of conventional as compared to germfree animals, demonstrating that “normal” propulsive activity is determined to a significant degree by the presence of the normal flora. This function of the flora has important implications for host defense. The precise mechanism of action of the flora is obscure.