Background: It is well established that the esophageal distention leads to gastric relaxation, partly by vago-vagal reflex but till now, the effect of esophageal distention on gastric acid secretion has not been investigated. The aim of this study was to investigate the effect of esophageal distention (ED) on basal and stimulated gastric acid secretion. Methods: Adult male Wistar rats (200-240g) were deprived of food but not water for 24 hrs before the experiments. Under urethane anesthesia (1.2 g/kg, i.p.), animals underwent tracheostomy and laparotomy. A catheter was inserted in the stomach through duodenum for gastric distention and gastric washout and the esophagus was cannulated with a distensible balloon orally to distend esophagus (0.3 ml, 10 min). Gastric acid secretion was stimulated by gastric distention, carbachol (4 µg/kg, i.p.) or histamine (5 mg/kg, s.c.). Effects of vagotomy, L-NAME (10 mg/kg, i.v.), L-arginine (500 mg/kg, i.p.) and hexamethonium were also investigated. Results: Esophageal distention reduces basal and gastric distention, carbachol and histamine stimulated acid secretion (P<0.05, P<0.0001, P<0.01 and P<0.02, respectively). Vagotomy reduced the inhibitory effect of the esophagus distention on gastric distention-induced acid secretion (P<0.05). Conclusion: These results indicate that vagus nerve involves in the inhibitory effect of the esophageal distention on the basal and stimulated gastric acid secretion. Nitric oxide (NO) may also be involved.

Keywords: esophageal distention, gastric acid secretion, nitric oxide, carbachol, histamine, vagotomy

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