In vitro sensitivity of mouse esophagus to agonists in different pH medium values.
OBJECTIVE
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.


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 degrees 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 Kirikkale 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.


CONCLUSIONS
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.
Soyer
Tutku
T
Department of Pediatric Surgery, Kirikkale University, Medical Faculty, Kirikkale 71100, Turkey. tutku@sanalofis.net
Keskil
Zuhal Aktuna
ZA
Somuncu
Salih
S
Aydos
Tolga Reşat
TR
Korkut
Oğuzhan
O
Kanmaz
Turan
T
Cakmak
Murat
M
D000109:Acetylcholine / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology*; D003470:Culture Media; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004947:Esophagus / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D011336:Probability; D012680:Sensitivity and Specificity; D046509:Tissue Culture Techniques
D000318:Adrenergic beta-Agonists; D018679:Cholinergic Agonists; D003470:Culture Media; D002217:Carbachol; D007545:Isoproterenol; D000109:Acetylcholine; D009638:Norepinephrine