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Peripheral chemoreceptor control of ventilation following sustained hypoxia in young and older adult humans
Author(s) -
Vovk Andrea,
Smith W. Donald F.,
Paterson Nicole D.,
Cunningham David A.,
Paterson Donald H.
Publication year - 2004
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.2004.027532
Subject(s) - hypoxia (environmental) , peripheral chemoreceptors , peripheral , chemoreceptor , anesthesia , medicine , respiration , ventilation (architecture) , ageing , chemistry , oxygen , anatomy , mechanical engineering , receptor , organic chemistry , engineering
The rate and duration of peripheral chemoreceptor resensitization following sustained hypoxia was characterized in young and older (74‐year‐old) adults. In addition, cerebral blood velocity (CBV) was measured in young subjects during and following the relief from sustained hypoxia. Following 20 min of sustained eucapnic hypoxia (50 mmHg), subjects were re‐exposed to brief (1.5 min) hypoxic pulses (50 mmHg), and the magnitude of the ventilatory response was used to gauge peripheral chemosensitivity. Five minutes after the relief from sustained hypoxia, ventilationincreased to 40.3 ± 4.5% of the initial hypoxic ventilatory response, and by 36 minincreased to 100%, indicating that peripheral chemosensitivity to hypoxia was restored. Theresponse magnitude plotted versus time demonstrated that, hence peripheral chemosensitivity, was restored at a rate of 1.9% per minute. Cerebral blood flow (CBF, inferred from CBV) remained constant during sustained hypoxia and increased by the same magnitude during the hypoxic pulses, suggesting that CBF has a small, if any, impact on the decline induring hypoxia and its subsequent recovery. To address the issue of whether hypoxic pulses affect subsequent challenges, series (continuous hypoxic pulses at various recovery intervals) and parallel (only 1 pulse per trial) methods were used. There were no differences in the ventilatory responses between the series and parallel methods. Older adults demonstrated a similar rate of recovery as in the young, suggesting that ageing in active older adults does not affect the peripheral chemoreceptor response.