Relationship Between Size of Bolus and the Act of Swallowing on Esophageal Peristalsis in Dogs

The respective roles that the act of swallowing and the presence of an esophageal bolus exert on the genesis of esophageal peristalsis were studied in dogs. In the absence of a bolus, peristalsis in the esophagus did not follow the act of swallowing, while in the absence of swallowing peristalsis did occur if the bolus was of adequate size. The size of the bolus required to induce esophageal peristalsis was significantly less when swallowing occurred than when it was absent. Thus, the threshold stimulus required to initiate peristalsis was related to the volume of bolus and the magnitude was reduced by the act of swallowing. When the size of the bolus was below a critical volume, peristalsis was not initiated even though this intraesophageal stimulus was reinforced by swallowing.