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09:54
A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
Cardioventilatory acclimatization induced by chronic intermittent hypoxia
R Iturriaga1, S Rey, R Del Rio
1Laboratory of Neurobiology, Faculty of Biological Sciences, P Universidad Católica de Chile, Santiago, Chile. riturriaga@bio.puc.cl
Advances in Experimental Medicine and Biology
|June 19, 2009
Summary
Chronic intermittent hypoxia (CIH) enhances carotid body (CB) reactivity to hypoxia, leading to early autonomic imbalance and hypertension. Short-term CIH alters heart rate variability (HRV) before blood pressure rises.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Regulation
- Respiratory Control
Background:
- Chronic intermittent hypoxia (CIH) is linked to hypertension in obstructive sleep apnea.
- Enhanced sympathetic outflow and carotid body (CB) potentiation are proposed mechanisms.
- Early changes preceding CIH-induced hypertension remain unclear.
Purpose of the Study:
- To investigate the effects of short- and long-term CIH on heart rate variability (HRV) in animals.
- To identify early autonomic changes associated with CIH-induced hypertension.
- To assess the role of CB chemosensory responses in CIH.
Main Methods:
- Exposure of cats and rats to controlled CIH conditions.
- Analysis of ventilatory responses to acute hypoxia.
- Assessment of arterial pressure and heart rate variability (HRV) power spectrum analysis.
Main Results:
- Short-term CIH (4 days) potentiated ventilatory response to hypoxia and shifted HRV spectrum, without altering arterial pressure.
- Long-term CIH (21 days) significantly increased arterial pressure and altered HRV spectrum.
- Early CIH exposure enhanced CB reactivity and ventilatory response to hypoxia.
Conclusions:
- Hypertension from long-term CIH is preceded by autonomic imbalance in HRV.
- Enhanced CB chemoreflex sensitivity to hypoxia contributes to CIH-induced hypertension.
- CIH rapidly enhances CB reactivity and alters autonomic balance, preceding hypertension.
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