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Repeated hypoxic exposures change respiratory chemoreflex control in humans
1Department of Physiology, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
The Journal of Physiology
|July 17, 2001
Summary
Repeated hypoxic exposure enhances ventilatory response by lowering the peripheral chemoreflex threshold. This adaptation occurs over 14 days, indicating a significant change in chemoreflex sensitivity to hypoxia.
Area of Science:
- Physiology
- Respiratory Medicine
- Neuroscience
Background:
- Chemoreflexes are crucial for regulating breathing.
- Hypoxia, a state of low oxygen, can impact chemoreflex function.
- Understanding adaptations to hypoxia is important for respiratory health.
Purpose of the Study:
- To investigate the effects of repeated hypoxic exposure on human chemoreflexes.
- To determine if daily hypoxic exposure alters ventilatory responses.
- To identify changes in chemoreflex sensitivity over 14 days.
Main Methods:
- Seven volunteers underwent daily 20-minute isocapnic hypoxia for 14 days.
- Chemoreflexes were measured before and after exposures using modified rebreathing tests.
- A crossover design with air exposure was used as a control.
Main Results:
- The ventilatory response to hypoxia significantly increased by day 14.
- The chemoreflex threshold in hypoxic conditions decreased over the 14 days.
- No significant changes were observed during air exposure control trials.
Conclusions:
- Repeated hypoxic exposure enhances the ventilatory response to hypoxia.
- This enhancement is mediated by a decrease in the peripheral chemoreflex threshold.
- The peripheral chemoreflex, not the central chemoreflex, is adapted by this protocol.