[The effect of experimental gastroesophageal reflux on the cough reflex in anesthetized cats].
BACKGROUND
Gastroesophageal reflux (GER) is a common cause of chronic cough. It has been suggested that GER most often causes chronic cough by stimulating the distal oesophagus. Possible mechanisms of this interactive process are: a) an oesophageal-tracheobronchial reflex, b) acid reflux seems to be only a cofactor of cough; it decreases cough threshold.


OBJECTIVE
To evaluate the effects of experimental GER on the cardiorespiratory parameters and on the cough induced by mechanical stimulation of airways mucosa in anaesthetised cats.


METHODS
In 10 adults cats of either sex, mean body weight 2.4 +/- 0.2 kg, anaesthetised with pentobarbitone sodium (30 mg/kg b.w., i.p.), oesophageal pressure, blood pressure, and volume tidal were recorded. 2 ml 0.1 N HCl was instilled into the isolated thoracic oesophagus with preserved innervation over a period of 5 minutes. The cough was induced by the insertion of nylon fibre into the airways and its intensity was evaluated from the changes in oesophageal pressure. Cough challenge was also repeated during intraesophageal instillation of 2 ml capsaicin (350 mumol/l). The parameters of cough intensity elicited during experimental GER were compared with the control cough parameters obtained during intraesophageal instillation of 2 ml physiological saline.


RESULTS
Intraesophageal instillation of either HCl or capsaicin was accompanied by the contractions of oesophageal wall and by the fluctuations in volume tidal. These changes were more pronounced after capsaicin challenge. There was no induction of either cough or other respiratory reflexes with forced expiration during the experimental GER. In other part of this study there were not obtained any significant differences of the intensity of mechanically-induced cough during intraesophageal instillation of physiological saline, HCl, and capsaicin.


CONCLUSIONS
The oesophageal-tracheobronchial reflex mechanism for either induction or modulation of cough is not present in healthy anaesthetised cats. We agree with previous data that GER alone is not trigger agent of cough. (Fig. 5, Ref. 17.)
Tatár
M
M
Ustav patologickej fyziológie, Jeseniovej Lekárskej fakulty, Univerzity Komenského, Martine, Slovakia. sd@doktor.jfmed.uniba.sk
Pécová
R
R
D000758:Anesthesia; D000818:Animals; D002211:Capsaicin / Q000008:administration & dosage; D002415:Cats; D003371:Cough / Q000503:physiopathology*; D004947:Esophagus / Q000503:physiopathology; D005260:Female; D005764:Gastroesophageal Reflux / Q000150:complications / Q000503:physiopathology*; D006851:Hydrochloric Acid / Q000008:administration & dosage; D008297:Male; D009119:Muscle Contraction; D010812:Physical Stimulation; D012018:Reflex; D012965:Sodium Chloride / Q000008:administration & dosage
D012965:Sodium Chloride; D006851:Hydrochloric Acid; D002211:Capsaicin
Vplyu experimentálneho gastroezofageálneho refluxu na kasel' u anestézovaných maciek.