Pyloric motor response to sympathetic nerve stimulation in dogs

Through this study we evaluated the effect of electrical stimulation of the greater splanchnic nerve on gastroduodenal motility in anesthetized dogs. The majority of stimulations (at a frequency of 10 Hz for 5 msec at a strength of 10V for a train of 10 sec) produced contractions in the gastric antrum and pylorus and relaxation in the duodenum. The antral, pyloric, and duodenal motor responses were unaffected by cervical vagosympathectomy, thoracic vagotomy, and adrenalectomy. Administration of phentolamine, propranolol, or hexamethonium and pretreatment with reserpine failed to affect the contractile gastroduodenal motor response. The inhibitory motor response in the duodenum was also unaffected by these surgical procedures and administration of drugs. After atropine administration, contractions induced by splanchnic nerve stimulation were abolished in the pylorus, as well as in the antrum and duodenum. Tetrodotoxin also abolished the gastroduodenal motor response. The greater splanchnic nerve contains an excitatory cholinergic pathway to the musculature of the pylorus.