Relationship of cervical and abdominal vagal activity to lower esophageal sphincter function.

The purpose of this study was to compare the effects of electrical stimulation of the abdominal and cervical portions of the vagus on lower esophageal sphincter (LES) pressure in the anesthetized opossum. Unilateral or bilateral abdominal vagotomy gave no significant change in basal LES pressure or in the sphincteric response to swallowing. Electrical stimulation of the peripheral end of the sectioned cervical vagus gave a frequency-related decrease in LES pressure with a maximum reduction of 93.5 +/- 2.5% at 10 HZ, 10 V. Stimulation of the central end of the cervical vagus increased LES pressure, with a maximum response of 34.0 +/- 1.9 mm Hg. Neither peripheral nor central stimulation of the sectioned abdominal vagus had significant effect on LES pressure (P greater than 0.05). Additionally, LES relaxation in response to swallowing or cervical vagal stimulation was intact after bilateral abdominal vagotomy. These studies suggest that whereas the cervical portion of the vagus mediates inhibitory and excitatory changes in LES pressure, the abdominal vagus has no demonstrable role in the control of LES function.