Laryngeal effects on respiratory pressures and timing in rabbits: role of the vagi.

Tidal breathing through a tracheostomy and through the larynx were compared in two groups of rabbits. Ten control and fourteen rabbits with chronically vagally denervated lungs were anaesthetized and spontaneously breathing. Inspiratory and expiratory tracheal pressure and timing components of respiratory pattern were measured in both groups of animals before and after carotid sinus/body denervation and cervical vagotomy. Breathing through the larynx significantly increased the inspiratory pressure and, to a lesser degree, affected expiratory pressure in both groups of animals and changed the respiratory timing by prolongation of TI and shortening of TE. Our results indicate that the larynx prominently influences pressures within the lower respiratory tract but its effect on the pattern of breathing is confined only to animals with an intact lung innervation.