Effects of caustic lye injury to the esophageal smooth muscle reactivity: in vitro study.

PURPOSE We investigated late effects of caustic lye injury on esophageal smooth muscle reactivity in the rat model. MATERIALS AND METHODS Male Sprague-Dawley rats were divided into two groups. Through a median laparatomy incision, abdominal esophageal segment was isolated. Orogastric and gastric (via gastrotomy) catheters were placed and tied over the isolated esophageal segment. Saline (0.9%) or 50% sodium hydroxide (1 ml) solution were instilled via orogastric catheter to the isolated segment in the control and caustic esophagus (CE group) groups, respectively. Then, the esophagus was rinsed with 0.9% saline via gastric catheter. The esophagus was removed and studied in organ chambers 28 days after the operation. RESULTS Carbachol- and KCl-induced contractile responses of esophageal smooth muscle were significantly reduced in the CE group with decreased E(max) value compared with the control group. Relaxant responses to serotonin were significantly reduced in the CE group with decreased E(max) value compared with the control group. No significant differences were found in E(max) and pD(2) values for papaverine acting on esophageal strips from the two groups. CONCLUSION The results provide evidence that, a surgically created caustic injury causes impaired smooth muscle reactivity that may contribute to esophageal motor dysfunction.