Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2014 Dec 1;99(12):1624-35.
doi: 10.1113/expphysiol.2014.080820. Epub 2014 Aug 28.

Increased blood-oxygen binding affinity in Tibetan and Han Chinese residents at 4200 m

T S Simonson  1 , G Wei  2 , H E Wagner  3 , T Wuren  2 , A Bui  3 , J M Fine  3 , G Qin  2 , F G Beltrami  4 , M Yan  2 , P D Wagner  3 , Ri Li Ge  2
Affiliations

Increased blood-oxygen binding affinity in Tibetan and Han Chinese residents at 4200 m

T S Simonson et al. Exp Physiol. .

Abstract

High-altitude natives are challenged by hypoxia, and a potential compensatory mechanism could be reduced blood oxygen-binding affinity (P50), as seen in several high-altitude mammalian species. In 21 Qinghai Tibetan and nine Han Chinese men, all resident at 4200 m, standard P50 was calculated from measurements of arterial PO2 and forehead oximeter oxygen saturation, which was validated in a separate examination of 13 healthy subjects residing at sea level. In both Tibetans and Han Chinese, standard P50 was 24.5 ± 1.4 and 24.5 ± 2.0 mmHg, respectively, and was lower than in the sea-level subjects (26.2 ± 0.6 mmHg, P < 0.01). There was no relationship between P50 and haemoglobin concentration (the latter ranging from 15.2 to 22.9 g dl(-1) in Tibetans). During peak exercise, P50 was not associated with alveolar-arterial PO2 difference or peak O2 uptake per kilogram. There appears to be no apparent benefit of a lower P50 in this adult high-altitude Tibetan population.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Bland-Altman plot comparing P50 estimates based on arterial blood cooximeter to forehead oximeter saturation measurements in seven sea level subjects (70-100% values, which are within the range examined in Tibetan and Han Chinese subjects examined at 4200 m, are included).Mean difference, standard deviation: (-0.87, 0.96); 95% confidence limits (-2.76, 1.01) are shown as dashed lines; a solid line indicates identity.
Figure 2
Figure 2
Bland-Altman plot comparing standard P50 calculated in 13 sea-level subjects based upon 1) the use of arterial plus venous (AV) saturation data to arterial (A) saturation data alone. Mean difference, standard deviation: (-0.2, 1.23). 95% confidence limits (-2.59, 2.23) are shown as dashed lines; a solid line indicates identity.
Figure 3
Figure 3
Data showing the relationship between P50 and [Hb] (A) and SaO2 during peak exercise (B). A) No relationship was found between [Hb] and P50. (B) Exercise SaO2 and P50 in Tibetan and Han Chinese subjects are significantly correlated. Han data are indicated by squares; low and high [Hb] in Tibetans indicated by open and closed circles, respectively.
Figure 4
Figure 4
Data showing the relationship between P50 and Alveolar-arterial PO2 difference (A), O2 extraction (B), and peak VO2/kg (C). Han data are indicated by squares; Tibetan data are indicated by circles. A low in vivo P50 did not affect these variables over the P50 range encountered.
Figure 5
Figure 5
Theoretical calculations of the Alveolar-arterial PO2 difference (AaPO2) (upper panel) and peripheral O2 extraction (lower panel) during peak exercise as a function of standard and in vivo P50 (ranges indicated by solid and dashed lines, respectively). While extraction increases essentially linearly with P50 over a wide range, AaPO2 falls with P50 only when the latter is lower than about 20 mmHg. These outcomes help explain the observations in Figure 4.
See this image and copyright information in PMC

Comment in

References

    1. Adams WH, Graves IL, Pyakural S. Hematologic observations on the yak. Proc Soc Exp Biol Med. 1975;148:701–705. - PubMed
    1. Beall CM, Cavalleri GL, Deng L, Elston RC, Gao Y, Knight J, Li C, Li JC, Liang Y, McCormack M, Montgomery HE, Pan H, Robbins PA, Shianna KV, Tam SC, Tsering N, Veeramah KR, Wang W, Wangdui P, Weale ME, Xu Y, Xu Z, Yang L, Zaman MJ, Zeng C, Zhang L, Zhang X, Zhaxi P, Zheng YT. Natural selection on EPAS1 (HIF2alpha) associated with low hemoglobin concentration in Tibetan highlanders. Proc Natl Acad Sci U S A. 2010;107:11459–11464. - PMC - PubMed
    1. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986;1(8476):307–310. - PubMed
    1. Brutsaert TD. Do high-altitude natives have enhanced exercise performance at altitude? Appl Physiol Nutr Metab. 2008;33:582–592. - PubMed
    1. Eaton JW, Skelton TD, Berger E. Survival at extreme altitude: protective effect of increased hemoglobin-oxygen affinity. Science. 1974;183:743–744. - PubMed

Publication types