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Ventilatory and intrapulmonary chemoreceptor sensitivity to CO2 in the burrowing owl
Respiration Physiology
|December 1, 1985
Summary
Burrowing owls exhibit a blunted ventilatory response to carbon dioxide (CO2) due to the lowest intrapulmonary chemoreceptor (IPC) CO2 sensitivity among studied birds. This adaptation may help them cope with naturally elevated CO2 levels.
Area of Science:
- Comparative physiology
- Avian respiration
- Chemoreception
Background:
- Intrapulmonary chemoreceptors (IPC) regulate avian breathing.
- Understanding CO2 sensitivity in birds is crucial for respiratory physiology.
Purpose of the Study:
- To measure ventilatory responses and IPC CO2 sensitivity in pigeons, burrowing owls, and geese.
- To investigate the physiological basis for burrowing owls' unique respiratory adaptations.
Main Methods:
- Anesthetized, unidirectionally ventilated birds were exposed to varying CO2 concentrations.
- Static CO2 sensitivity of IPC was determined by receptor discharge frequency.
- Linear regressions analyzed receptor discharge frequency against ln(PICO2).
Main Results:
- Burrowing owls showed significantly reduced respiratory frequency and amplitude responses to elevated CO2 compared to pigeons.
- The static CO2 sensitivity of IPC was lowest in burrowing owls (-6.87 imp/sec . ln(PICO2)) compared to geese and pigeons.
- IPC CO2 sensitivity distribution was skewed in burrowing owls, making median sensitivity (-5.50 imp/sec . ln(PICO2)) more representative.
Conclusions:
- Burrowing owls possess the lowest reported static CO2 sensitivity of IPC among euthermic birds.
- This reduced sensitivity likely contributes to their blunted ventilatory response to elevated CO2.
- This adaptation may be crucial for survival in their natural, high-CO2 environment.