Vagal esophageal receptors in anesthetized dogs: mechanical and chemical responsiveness.

This study was performed to evaluate the characteristics of esophageal receptors in anesthetized and artificially ventilated dogs. The electrical activity of the esophageal afferents was recorded from the peripheral cut end of the cervical vagus nerve. A cuffed catheter was inserted into the esophagus at the level of the third tracheal ring and was used to establish the esophageal location of the endings.

Larynx vs. esophagus as reflexogenic sites for acid-induced bronchoconstriction in dogs.

Bronchoconstriction in asthmatic patients is frequently associated with gastroesophageal reflux. However, it is still unclear whether bronchoconstriction originates from the esophagus or from aspiration of the refluxate into the larynx and larger airway. We compared the effect of repeated esophageal and laryngeal instillations of HCl-pepsin (pH 1.

Endotracheal cuff pressure as an index of airway smooth muscle activity: comparison with total lung resistance.

Pressure changes in the cuff of an endotracheal tube (Pcuff) were measured as an index of the tracheal smooth muscle activity and compared with total lung resistance (RL) in anesthetized, paralyzed and artificially ventilated dogs. After obtaining passive pressure-volume relationships of the cuff in situ, we activated the airway smooth muscle by electrical stimulation of the right vagus nerve, intravenous acetylcholine, and airway mechanical stimulation. The responses elicited by vagal stimulation and airway probing affected predominantly the tracheal smooth muscle, whereas acetylcholine administration caused homogeneous responses in Pcuff and RL, suggesting involvement of the smooth muscle of the entire airway.

Effects of HCl-pepsin laryngeal instillations on upper airway patency-maintaining mechanisms.

Gastroesophageal reflux has been indicated as an etiopathological factor in disorders of the upper airway. Upper airway collapsing pressure stimulates pressure-responsive laryngeal receptors that reflexly increase the activity of upper airway abductor muscles. We studied, in anesthetized dogs, the effects of repeated laryngeal instillations of HCl-pepsin (HCl-P; pH = 2) on the response of laryngeal afferent endings and the posterior cricoarytenoid muscle (PCA) to negative pressure.

Action of moguisteine on the activity of tracheobronchial rapidly adapting receptors in the dog.

We have studied the effects of moguisteine, a new non-narcotic, peripherally acting antitussive compound, on tracheobronchial rapidly adapting irritant receptors (RARs). Experiments were carried out on dogs anaesthetized with a mixture of urethane and alpha-chloralose, paralysed with gallamine, vagotomized and artificially ventilated. Single unit action potentials identified as originating from tracheobronchial RARs were recorded from the peripheral cut end of the right vagus nerve.