In vitro sensitivity of mouse esophagus to agonists in different pH medium values Tutku Soyer a, ⁎ , Zuhal Aktuna Keskil b , Salih Somuncu a , Tolga Reşat Aydos b , Oğuzhan Korkut b , Turan Kanmaz a , Murat Çakmak a a Department of Pediatric Surgery, Kırıkkale University, Medical Faculty, Kırıkkale 71100, Turkey b Department of Pharmacology, Kırıkkale University, Medical Faculty, Kırıkkale 71100, Turkey Received 13 June 2007; revised 27 July 2007; accepted 2 August 2007 Index words: Esophagus; Agonist; pH Abstract Aim: The aim of this study is to determine the in vitro sensitivity of mouse esophagus to contracting and relaxing agonists in different pH medium values. Materials and Methods: Forty-eight Swiss albino mice (30-40 g) of both sexes were anesthetized with tiopental sodium (30 mg/kg). After exsanguinations from abdominal artery, esophagi were removed and suspended under 0.6 g of resting tension in a tissue bath containing 10 mL of Krebs solution at 37°C. The experiments were performed in different pH mediums 7.4, 6.4, 4, and 2. Carbachol and acetylcholine were used as contractile agonists, and noradrenalin and isoproterenol to evaluate relaxation responses. Data concerning similar concentrations of contractile agonists obtained from different pH mediums were analyzed using Kruskal-Wallis nonparametric analysis of variance and post hoc Dunn test. Relaxation responses were compared with Student t test. A P value less than .05 was considered significant. The study was approved by Local Ethical Committee of Kırıkkale University. Results: Carbachol and acetylcholine caused concentration-dependent contractility in pH 7.4, 6.4, and 4, but contractile responses were inhibited in pH 2. In carbachol and acetylcholine experiments, there was a significant decrease in contractile responses to all concentrations in conjunction with a decreased in pH value. Relaxation responses in pH 2 and 4 could not be obtained because precontraction of tissues was not possible. Noradrenalin and isoproterenol produced concentration- dependent relaxations in pH 7.4 and 6.4. Although noradrenalin responses showed no significant difference according to pH, isoproterenol caused better relaxations in pH 6.4 (between 10 -8 and 10 -6 mol/L) when compared to pH 7.4 studies. Conclusion: The mouse esophagus has impaired contractile responses to carbachol and acetylcholine in decreased pH values. Contraction responses did not occur in pH medium of 2. In contrast, esophagus segments showed better relaxations in lower pH values with isoproterenol. © 2007 Elsevier Inc. All rights reserved. Presented at the 40th annual meeting of the Pacific Association of Pediatric Surgeons, Queenstown, New Zealand, April 15-19, 2007. This study was presented at the Eighth European Congress of Pediatric Surgeons in Turin, Italy, May 16-19, 2007. ⁎ Corresponding author. Tel.: +90 532 6651960. E-mail address: tutku@sanalofis.net (T. Soyer). www.elsevier.com/locate/jpedsurg 0022-3468/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2007.08.006 Journal of Pediatric Surgery (2007) 42, 1988–1992