Breathing pattern in anesthetized chickens: CO2 inhalation and vagotomy.

The breathing patterns of 20 anesthetized chickens were studied during progressive suppression of intrapulmonary chemoreceptors (IPC) by various concentrations of CO2 and following bilateral vagotomy. The vagotomy breathing pattern, characterized by a marked accentuation of expiratory times with prolonged expiratory pauses, was markedly different from that induced by CO2 inhalation. Removal of neural input to the central respiratory centers from IPC does not appear to be solely responsible for the altered breathing pattern following vagotomy in birds.