Change of lower esophageal sphincter pressure in rabbits by Teflon injection.

BACKGROUND: The mechanically incompetent lower esophageal sphincter (LES) plays a key role in patients with gastroesophageal reflux disease. The purpose of the study was to assess the pressure changes of LES in rabbits by intraabdominal injection of Teflon paste (Polytetrafluoroethylene) at the gastroesophageal junction. METHODS: New Zealand white breed of rabbits were used in these studies. The anesthetized rabbit was injected with a 21-gauge needle and a syringe loaded with Teflon paste. The injection sites were around the gastroesophageal junction. LES pressure was measured by conventional methods using a water-filled infused system. The pressure gradient was measured immediately before and after the injection as well as by a weekly measurement over four weeks. The histologic characteristics of the injection sites were studied four weeks later. RESULTS: The mean pressure gradient of LES of twelve rabbits of immediate preinjection and post-injection was 29.71 +/- 8.10 mmHg and 37.58 +/- 10.69 mmHg (mean +/- S.D.), respectively (p value, 0.0329) Animals were followed upifor from one to four weeks, and were then sacrificed. The mean pressure gradient of LES of the twelve rabbits in the first week, the second week, the third week and the fourth week was 37.80 +/- 11.36 mmHG, 35.77 +/- 3.54 mmHg, 33.42 +/- 4.95 mmHg and 32.68 +/- 4.62 mmHg (mean +/- S.D.), respectively. Compared to pre-injection data, a significant difference was found in the first week and the second week (p value, 0.0342 and 0.0281, respectively). Gross examination of the gastroesophageal regions showed a welldefined Teflon mass of firm consistency at the site of the injection. Histological examination showed encapsulation of the implant by a thin layer of fibrous tissue and a benign foreign body granulomatous reaction with round cells surrounding the implant. CONCLUSIONS: It is technically feasible to produce experimentally pressure changes of LES in rabbits by intraabdominal injection of Teflon paste. Nevertheless, the clinical validity on patients with gastroesophageal reflux induced by the incompetence of LES remains to be verified.