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Ventilatory changes during intermittent hypoxia: importance of pattern and duration
Nanduri R Prabhakar1, David D Kline
1Department of Physiology and Biophysics, School of Medicine, 10900 Euclid Avenue, Case Western Reserve University, Cleveland, OH, 44106, USA. nrp@po.cwru.edu
High Altitude Medicine & Biology
|August 7, 2002
Summary
Intermittent hypoxia from recurrent apneas or high altitude affects breathing control differently. Mechanisms vary, impacting hypoxic ventilatory response (HVR) and long-term facilitation (LTF).
Area of Science:
- Physiology
- Respiratory Control
- Hypoxia Research
Background:
- Intermittent hypoxia (IH) is more common than sustained hypoxia.
- IH occurs in conditions like recurrent apneas and high-altitude exposure.
- Understanding IH's long-term effects on breathing control is crucial.
Purpose of the Study:
- To review the long-term consequences of IH on respiratory control.
- To differentiate effects of IH associated with recurrent apneas versus high-altitude ascents.
- To explore underlying mechanisms, including carotid body sensitivity and HIF-1.
Main Methods:
- Review of studies on chronic recurrent apneas and repeated high-altitude ascents.
- Analysis of animal models (rat) examining carotid body sensitivity.
- Investigation of long-term facilitation (LTF) of respiratory motor output.
Main Results:
- Recurrent apneas can depress or enhance hypoxic ventilatory response (HVR) and often depress hypercapnic ventilatory response (HCVR).
- High-altitude ascents augment HVR with minimal effect on HCVR.
- IH simulating apneas enhances carotid body sensitivity; IH simulating ascents has less peripheral effect.
Conclusions:
- The impact of IH on ventilatory control depends on the specific exposure pattern.
- Different IH paradigms activate distinct mechanisms, affecting HVR and potentially involving HIF-1.
- Further research is needed to elucidate molecular pathways in IH-induced ventilatory control changes.