BACKGROUND & AIMS: Surgical fundoplication is an effective treatment for gastroesophageal reflux disease. One of the proposed mechanisms for its antireflux action is that it reduces lower esophageal sphincter (LES) relaxation. We investigated whether fundoplication works through a stretch-sensitive mechanism of LES relaxation. METHODS: Studies were performed in rats. Intravenous and arterial lines were placed and tracheal intubation was performed. A midline laprotomy was performed to place sutures through the esophagus to exert axial stretch on the LES, and the vagus nerve was isolated in the neck for electrical stimulation. The LES pressure was monitored with a 2F solid-state pressure transducer placed through a gastrostomy. Cranial displacement of the LES was recorded using piezoelectric crystals. Data were recorded before and after 360-degree Nissen fundoplication. RESULTS: Axial stretch and vagus nerve stimulation induced cranial displacement of the LES as well as LES relaxation in a dose-dependent manner. LES relaxation and axial stretch were each significantly reduced after fundoplication (P < .01). Nitric-oxide-induced LES relaxation was not affected by fundoplication. Removal of fundoplication restored axial stretch- and vagus nerve-stimulated LES relaxation as well as LES cranial displacement. CONCLUSIONS: Fundoplication reduces LES relaxation by interfering with axial stretch on the LES. Based on this mechanism of the antireflux actions of fundoplication, it might be possible to design new surgical strategies to treat reflux disease and reduce complications of fundoplication surgery.
BACKGROUND & AIMS: Surgical fundoplication is an effective treatment for gastroesophageal reflux disease. One of the proposed mechanisms for its antireflux action is that it reduces lower esophageal sphincter (LES) relaxation. We investigated whether fundoplication works through a stretch-sensitive mechanism of LES relaxation. METHODS: Studies were performed in rats. Intravenous and arterial lines were placed and tracheal intubation was performed. A midline laprotomy was performed to place sutures through the esophagus to exert axial stretch on the LES, and the vagus nerve was isolated in the neck for electrical stimulation. The LES pressure was monitored with a 2F solid-state pressure transducer placed through a gastrostomy. Cranial displacement of the LES was recorded using piezoelectric crystals. Data were recorded before and after 360-degree Nissen fundoplication. RESULTS: Axial stretch and vagus nerve stimulation induced cranial displacement of the LES as well as LES relaxation in a dose-dependent manner. LES relaxation and axial stretch were each significantly reduced after fundoplication (P < .01). Nitric-oxide-induced LES relaxation was not affected by fundoplication. Removal of fundoplication restored axial stretch- and vagus nerve-stimulated LES relaxation as well as LES cranial displacement. CONCLUSIONS: Fundoplication reduces LES relaxation by interfering with axial stretch on the LES. Based on this mechanism of the antireflux actions of fundoplication, it might be possible to design new surgical strategies to treat reflux disease and reduce complications of fundoplication surgery.