6 How exposure of the pharyngeal cavity to CO_2 affects the negative pressure airway reflex

Abstract

We evaluated how exposure of the pharyngeal mucous membrane in rabbits to carbon dioxide (662) affects the negative pressure airway reflex (NPAR) using the activity of the genioglossal muscle as an index of NPAR. Exposure of the pharyngeal cavity to air containing 1096 CO2 significantly inhibited NPAR, while treatment with methazolamide (MZ) prevented inhibition of NPAR caused by CO_2 exposure. The magnitude of decrease in pH in the pharyngeal submucosa that resulted from CO_2 exposure was smaller in animals with MZ treatment than in those without. These results suggest that inhibition of NPAR by CO_2 exposure may be associated with change in the pH of the pharyngeal tissues.