Effect of bilateral cervical vagotomy on balloon-induced lower esophageal sphincter relaxation in the dog

A study was performed in dogs to determine whether balloon distension within the striated muscle esophagus induces lower esophageal sphincter relaxation via a local intramural pathway or a central neural pathway. Bilateral vagosympathetic nerve blockade was produced by cooling the nerve trunks isolated in skin loops on either side of the neck. Sphincter pressure was measured before and during intraesophageal balloon distension, with and without nerve blockade. With the vagosympathetic nerves intact, balloon distension produced sphincter relaxation, sphincter shortening, and orad movement of the sphincter. The threshold for these responses increased progressively as distension was applied at more proximal levels. Bilateral vagosympathetic nerve blockade abolished all the lower esophageal sphincter responses to distension at any level within the esophagus, whether or not sphincter pressure was raised by pentagastrin infusion. Therefore, lower esophageal sphincter relaxation induced by distension of the dog striated muscle esophagus requires a central nervous system connection via the vagosympathetic nerve trunks. There is no direct intramural pathway for this responses in the dog.