Contribution of Gular Pumping to Lung Ventilation in Monitor Lizards

A controversial hypothesis has proposed that lizards are subject to a speed-dependent axial constraint that prevents effective lung ventilation during moderate- and high-speed locomotion. This hypothesis has been challenged by results demonstrating that monitor lizards (genus Varanus) experience no...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 1999-06, Vol.284 (5420), p.1661-1663
Main Authors: Owerkowicz, Tomasz, Farmer, Colleen G., Hicks, James W., Brainerd, Elizabeth L.
Format: Article
Language:English
Subjects:
Air breathing
Animals
Biological and medical sciences
Blood-vessels
Endurance
Energy Metabolism
Fundamental and applied biological sciences. Psychology
Gait
Iguanas
Iguanas - physiology
Lizards
Lizards - physiology
Locomotion
Lungs
Oxygen Consumption
Pharynx - physiology
Physiological aspects
Pressure
Pulmonary circulation
Pulmonary Gas Exchange
Pulmonary Ventilation
Pumping
Pumps
Reptiles & amphibians
Respiratory system: anatomy, metabolism, gas exchange, ventilatory mechanics, respiratory hemodynamics
Treadmills
Ventilation
Ventilation systems
Vertebrates: respiratory system
Zoology
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Summary:A controversial hypothesis has proposed that lizards are subject to a speed-dependent axial constraint that prevents effective lung ventilation during moderate- and high-speed locomotion. This hypothesis has been challenged by results demonstrating that monitor lizards (genus Varanus) experience no axial constraint. Evidence presented here shows that, during locomotion, varanids use a positive pressure gular pump to assist lung ventilation. Disabling the gular pump reveals that the axial constraint is present in varanids but it is masked by gular pumping under normal conditions. These findings support the prediction that the axial constraint may be found in other tetrapods that breathe by costal aspiration and locomote with a lateral undulatory gait.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.284.5420.1661