The in-vivo oxyhaemoglobin dissociation curve at sea level and high altitude |
| |
| Authors: | Dahlia Y Balaban James Duffin David Preiss Alexandra Mardimae Alex Vesely Marat Slessarev GR Zubieta-Calleja Ernest R Greene David B MacLeod Joseph A Fisher |
| |
| Institution: | 1. Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada;2. Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada;3. Department of Anaesthesiology, University of Toronto, and University Health Network, Toronto, ON, Canada;4. Department of Anesthesiology, Massachusetts General Hospital, Boston, USA;5. Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;6. Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada;g High Altitude Pathology Institute, La Paz, Bolivia;h New Mexico Highlands University, Las Vegas, NM 87701, USA;i Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA |
| |
| Abstract: | Animals native to hypoxic environments have adapted by increasing their haemoglobin oxygen affinity, but in-vitro studies of the oxyhaemoglobin dissociation curve (ODC) in humans show no changes in affinity under physiological conditions at altitudes up to 4000 m. We conducted the first in-vivo measurement of the ODC; inducing progressive isocapnic hypoxia in lowlanders at sea level, acutely acclimatized lowlanders at 3600 m, and native Andeans at that altitude. ODC curves were determined by administering isocapnic steps of increasing hypoxia, and measuring blood oxygen partial pressure and saturation. The ODC data were fitted using the Hill equation and extrapolated to predict the oxygen partial pressure at which haemoglobin was 50% saturated (P50). In contrast to findings from in-vitro studies, we found a pH-related reduction in P50 in subjects at altitude, compared to sea-level subjects. We conclude that a pH-mediated increase in haemoglobin oxygen affinity in-vivo may be part of the acclimatization process in humans at altitude. |
| |
| Keywords: | Carbon dioxide Hypoxia Haemoglobin oxygen saturation O2 dissociation curve Humans Andeans High altitude |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
