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This Article Full Text Full Text (PDF) All Versions of this Article: 89/6/647    most recent expphysiol.2004.027532v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Vovk, A. Articles by Paterson, D. H Search for Related Content PubMed PubMed Citation Articles by Vovk, A. Articles by Paterson, D. H Related Collections Respiratory

¹ Canadian Centre for Activity and Ageing² School of Kinesiology³ Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario N6A 3K7, Canada ⁴ Countess of Chester Hospital, Liverpool Road, Chester CH2 1UL, UK

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, ventilation increased to 40.3 ± 4.5% of the initial hypoxic ventilatory response, and by 36 min increased to 100%, indicating that peripheral chemosensitivity to hypoxia was restored. The response 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 in during 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.

(Received 7 March 2004; accepted after revision 14 July 2004; first published online 15 July 2004)
Corresponding author Donald H. Paterson, Canadian Centre for Activity and Ageing, 1490 Richmond Street, London, Ontario, Canada, N6G 2M3. Email: dpaterso{at}uwo.ca