Related Experiment Videos
Pulmonary gas exchange in panting dogs.
1Department of Physiology, Max Planck Institute for Experimental Medicine, Göttingen, Federal Republic of Germany.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|March 1, 1989
Summary
Panting dogs in heat maintain stable body temperature by rapidly increasing breathing rate. This panting, however, leads to significant physiological dead space, impacting effective pulmonary gas exchange.
Area of Science:
- Physiology
- Respiratory System
- Thermoregulation
Background:
- Panting is a common thermoregulatory mechanism in many mammals.
- Understanding the efficiency of gas exchange during panting is crucial for respiratory physiology.
Purpose of the Study:
- To investigate pulmonary gas exchange during panting in dogs exposed to elevated ambient temperatures.
- To quantify the impact of panting on alveolar ventilation and gas composition.
Main Methods:
- Seven conscious dogs with chronic tracheostomy and exteriorized carotid artery loops were studied.
- Animals were exposed to 27.5°C and 65% relative humidity for 2 hours.
- Mass spectrometry monitored O2 and CO2 in the tracheostomy tube; blood gases (PaO2, PaCO2) were measured from the carotid artery.
Main Results:
- Dogs exhibited shallow panting at ~313 breaths/min, maintaining core body temperature.
- Effective alveolar ventilation was 5.5 L/min with PaO2 of 106.2 Torr and PaCO2 of 27.2 Torr.
- Significant end-tidal-arterial differences for O2 (26.0 Torr) and CO2 (14.9 Torr) indicated inefficient gas exchange.
Conclusions:
- Panting in dogs under heat stress results in substantial physiological dead space, accounting for 54% of alveolar ventilation.
- Inefficiency in gas mixing, suggested by expirogram steepness, contributes to the large gas exchange gradients observed.
- While effective for thermoregulation, panting poses challenges for optimal pulmonary gas exchange.