Direct P CO 2 measurements in the dorso-bronchial gas of awake peking ducks: Evidence for a physiological role of the neopulmo in respiratory gas exchanges

Abstract

1. P co 2 values in the gas of the abdominal air sac ( abs), posterior secondary bronchi ( psb), interclavicular air sac ( ics), and in the expired gas at the nostril were measured in four conscious Peking ducks by rapid infra-red CO 2-analyzers during normal resting ventilation. 2. The results indicate that 1° during inspiration, psb received a part of the inspired ambient air; 2° during expiration, CO 2 molecules were added into the flowing gas first on its way from abs to psb, and secondly on its way from psb to ics. 3. The study gives new evidence for a unidirectional caudal-cephalad gas flow through the avian lung, and shows that both neopulmo and paleopulmo play a role in the resting respiratory gas exchanges of birds.