BACKGROUND & AIMS: Gastroesophageal reflux frequently occurs during spontaneous transient lower esophageal sphincter relaxations (TLESRs). The aim of this study was to determine the motor activity in the body of the esophagus during TLESRs in 10 healthy subjects. METHODS: Esophageal contractions were recorded 13,8,and 3 cm above a sleeve that measured LES pressure. A balloon was inflated 8 cm above the sleeve to induce an esophageal tonic contraction (artificial high-pressure zone). RESULTS: No relaxation of the artificial high-pressure zone was detected at the onset or during spontaneous TLESRs before gastroesophageal reflux. Esophageal acidification provoked no changes or increased the pressure in the artificial high-pressure zone by 47.9% +/- 12% When gastroesophageal reflux abruptly distended the esophagus (common cavity), a relaxation of the artificial high-pressure zone of 51.1% +/- 6.6% was observed in 78% of the instances. Deglutitive or secondary contractions during spontaneous TLESRs traveled down the esophagus in 96.5% of the instances. CONCLUSIONS: Stimuli that induced spontaneous TLESRs did not by themselves inhibit muscle contractility in the body of the esophagus. Acidification without distention of the lower esophagus frequently increased esophageal tonic contractility. Abrupt lower esophageal distention by reflux of air or acid partially relaxed the artificial high-pressure zone in the esophageal body, probably to assist gastric venting.