Effect of Regulatory Peptides on the Vagally Stimulated Lower Esophageal Sphincter Pressure in Pigs

Abstract

The effect of vasoactive intestinal polypeptide (VIP), enkephalin, neuropeptide Y, gastrin, cholecystokinin, neurotensin, somatostatin, and thyrotropin-releasing hormone on the lower esophageal sphincter pressure (LESP) was studied in anesthetized pigs. The peptides were infused into the arterial supply of the lower esophageal sphincter in graded doses during electrical stimulation of the vagal nerve (9 V, 10 Hz, 3 msec). The vagally stimulated LESP was inhibited by VIP (0-40 pmol/ kg/min) and enkephalin (0-200 pmol/kg/min) in a dose-dependent manner. The other peptides had no effect on the stimulated LESP regardless of the dose tested. The results suggest that VIP and enkephalin may influence the stimulated LESP under normal conditions and that the other peptides tested did not affect the physiological regulation of the LESP. Furthermore, the vagally stimulated LESP was inhibited by atropine (250 g/kg intravenously) but not by guanethidine (1 mg/kg intravenously).

Key Words:

• Cholecystokinin
• enkephalin
• esophagus
• gastrin
• neuropeptide Y
• neurotensin
• somatostatin
• thyrotropin-releasing hormone
• vagal stimulation
• vasoactive intestinal polypeptide