Differences in the control of breathing between Himalayan and sea-level residents

Autor: Marat Slessarev, M Kunzang, Rebecca R. Watson, Joseph A. Fisher, Dennis Jensen, Angchuk Norboo, Richard E. Greene, James Duffin, Tsering Stobdan, Eitan Prisman, Otto Appenzeller, Tsering Norboo, S. Ito, David Preiss, D Diskit
Rok vydání: 2010
Předmět:
Zdroj: The Journal of Physiology. 588:1591-1606
ISSN: 0022-3751
DOI: 10.1113/jphysiol.2009.185504
Popis: We compared the control of breathing of 12 male Himalayan highlanders with that of 21 male sea-level Caucasian lowlanders using isoxic hyperoxic (= 150 mmHg) and hypoxic (= 50 mmHg) Duffin's rebreathing tests. Highlanders had lower mean ±s.e.m. ventilatory sensitivities to CO2 than lowlanders at both isoxic tensions (hyperoxic: 2.3 ± 0.3 vs. 4.2 ± 0.3 l min−1 mmHg−1, P= 0.021; hypoxic: 2.8 ± 0.3 vs. 7.1 ± 0.6 l min−1 mmHg−1, P < 0.001), and the usual increase in ventilatory sensitivity to CO2 induced by hypoxia in lowlanders was absent in highlanders (P= 0.361). Furthermore, the ventilatory recruitment threshold (VRT) CO2 tensions in highlanders were lower than in lowlanders (hyperoxic: 33.8 ± 0.9 vs. 48.9 ± 0.7 mmHg, P < 0.001; hypoxic: 31.2 ± 1.1 vs. 44.7 ± 0.7 mmHg, P < 0.001). Both groups had reduced ventilatory recruitment thresholds with hypoxia (P < 0.001) and there were no differences in the sub-threshold ventilations (non-chemoreflex drives to breathe) between lowlanders and highlanders at both isoxic tensions (P= 0.982), with a trend for higher basal ventilation during hypoxia (P= 0.052). We conclude that control of breathing in Himalayan highlanders is distinctly different from that of sea-level lowlanders. Specifically, Himalayan highlanders have decreased central and absent peripheral sensitivities to CO2. Their response to hypoxia was heterogeneous, with the majority decreasing their VRT indicating either a CO2-independent increase in activity of peripheral chemoreceptor or hypoxia-induced increase in [H+] at the central chemoreceptor. In some highlanders, the decrease in VRT was accompanied by an increase in sensitivity to CO2, while in others VRT remained unchanged and their sub-threshold ventilations increased, although these were not statistically significant.
Databáze: OpenAIRE
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