scholarly journals Hemoglobin–oxygen affinity in high-altitude vertebrates: is there evidence for an adaptive trend?

2016 ◽  
Vol 219 (20) ◽  
pp. 3190-3203 ◽  
Author(s):  
Jay F. Storz
Keyword(s):  
High Altitude ◽  
Oxygen Affinity ◽  
Hemoglobin Oxygen Affinity

High Altitude Genetic Adaptation In Tibetans Does Not Include Increased Hemoglobin-Oxygen Affinity

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 937-937
Author(s):  
Tsewang Tashi ◽  
Dottie Hussey ◽  
Felipe R Lorenzo V ◽  
Parvaiz Koul ◽  
Josef T. Prchal
Keyword(s):  
High Altitude ◽  
Salt Lake ◽  
Venous Blood ◽  
Salt Lake City ◽  
Oxygen Affinity ◽  
Hill Coefficient ◽  
Genetic Adaptation ◽  
Hemoglobin Oxygen Affinity ◽  
Hemoglobin Variants ◽  
Lake City

Abstract Increased hemoglobin-oxygen affinity has been shown to be an adaptive response to hypoxia in many high altitude animals such as the Andean goose, guinea pig and llamas (Reynafarje C. 1975; Hebbel R. 1978). It has been reported that people living in a high altitude, hypoxic environment have also developed a similar adaptation. Native Tibetans are known to have lived at an average of 3000-5000 meters on the Tibetan Plateau for more than 20,000 years, and have undergone genetic adaptations that have enabled them to thrive in this reduced oxygen environment. Most Tibetans are thus protected from polycythemia and other features of chronic mountain sickness. Several studies have reported higher arterial oxygen saturations among Tibetans as part of their genetic adaptation (Beall C. 1994; Moore L. 2001; Niermeyer S. 1995), thereby concluding that they have higher hemoglobin-oxygen affinity. Further, recent genomic studies have reported that beta-globin haplotypes (HBB and HBG2) have been selected in Tibetans, suggesting the presence of hemoglobin variants as a beneficial factor of Tibetan adaptation (Yi. 2010). However, some of the reports of increased hemoglobin-oxygen affinity are based on single readings of arterial oxygen measurements. Hemoglobin-oxygen affinity is more optimally measured by deriving the P50 value, which is the partial pressure of oxygen at which hemoglobin is 50% saturated with oxygen. A decreased P50 can be due to mutated globin genes resulting in high oxygen affinity hemoglobins, low 2,3 BPG, high pH or low temperature. The hemoglobin-oxygen dissociation is optimally derived by hemoximeter measurements of the percent saturation of hemoglobin at various partial pressures of oxygen. The resultant curve has a sigmoid shape due to the cooperative binding of oxygen to the four globins in the hemoglobin tetramer; this cooperative interaction can be enumerated as a Hill coefficient “n”. If a hemoximeter is not readily available, the P50 can be estimated from the venous blood gas using the measured pO2, hemoglobin oxygen percent saturation O2%, and pH (Lichtman M. 1976); however the Hill coefficient “n” cannot be derived by this method. To definitely establish whether the Tibetan adaptation to high altitude hypoxia involves increased hemoglobin-oxygen affinity, we conducted the following study of direct and indirect oxygen-hemoglobin affinity among Tibetans living at two different altitudes. We enrolled 14 healthy ethnic Tibetans and one closely related Nepalese Sherpa. There were 8 males and 7 females ages ranging 35-75 years. The first group consisted of 5 ethnic Tibetans living in Srinagar, India (1,600 meters), on whom venous blood gases were done and the P50 was derived using pH, PO2 and O2 saturation using the formula described by Lichtman and colleagues. Three were born in Tibet and two were offspring of Tibet-born parents. The second group consisted of 10 volunteers (9 Tibetans and one Nepalese Sherpa) residing in Salt Lake City, UT, (1,300 meters) whose peripheral blood was evaluated by Hemox Analyzer for obtaining P50 values and “n” Hill coefficients for hemoglobin oxygen binding. All the ethnic Tibetans in Salt Lake City were born in Tibet except for one, and the Nepalese Sherpa was born in Nepal. The results are depicted in Table. The P50 measured by venous blood gases on the Tibetan volunteers from Srinagar, India and those measured by Hemox Analyzer on the 10 volunteers from Salt Lake City, UT were normal, with values in the normal range (22-28 mmHg). No hemoglobin variants were detected by high pressure liquid chromatography in these 15 Tibetan volunteers.TableSubject IDP50 (mmHg)“n” Hill CoefficientS 0526.38n/aS 0825.95S 1326.55S 1523.68S 2722.72U 1926.962.97U 2025.162.83U 2124.202.89U 2225.462.84U 2322.502.89U 2424.062.87U 2524.282.83U 2622.352.82U 2723.292.79U 2825.992.75 We report no evidence for the presence of high hemoglobin-oxygen affinity in Tibetans as a constituent of their genetic adaptation. Our data rule out the existence of hemoglobin variants and aberrant 2,3 BPG metabolism as possible features of Tibetan high-altitude adaptation; however acquired transient metabolic alterations at high altitudes, cannot be excluded to account for possible changes in hemoglobin-oxygen affinity but these are not evolved persistent features of Tibetan genetic adaptation. Studies of Tibetans living in these extreme hypoxic environment (>4,000m) are now planned. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Alteration of the α1β2/α2β1 subunit interface contributes to the increased hemoglobin-oxygen affinity of high-altitude deer mice

PLoS ONE ◽  
2017 ◽  
Vol 12 (3) ◽  
pp. e0174921 ◽  
Author(s):  
Noriko Inoguchi ◽  
Nobuhiro Mizuno ◽  
Seiki Baba ◽  
Takashi Kumasaka ◽  
Chandrasekhar Natarajan ◽  
...  
Keyword(s):  
High Altitude ◽  
Oxygen Affinity ◽  
Deer Mice ◽  
Subunit Interface ◽  
Hemoglobin Oxygen Affinity

scholarly journals Influence of High Hemoglobin-Oxygen Affinity on Humans During Hypoxia

2022 ◽  
Vol 12 ◽  
Author(s):  
Kevin L. Webb ◽  
Paolo B. Dominelli ◽  
Sarah E. Baker ◽  
Stephen A. Klassen ◽  
Michael J. Joyner ◽  
...  
Keyword(s):  
High Altitude ◽  
Oxygen Delivery ◽  
Physiological Responses ◽  
Oxygen Affinity ◽  
Genetic Mutations ◽  
Central Question ◽  
Hemoglobin Oxygen Affinity ◽  
Insight Into

Humans elicit a robust series of physiological responses to maintain adequate oxygen delivery during hypoxia, including a transient reduction in hemoglobin-oxygen (Hb-O2) affinity. However, high Hb-O2 affinity has been identified as a beneficial adaptation in several species that have been exposed to high altitude for generations. The observed differences in Hb-O2 affinity between humans and species adapted to high altitude pose a central question: is higher or lower Hb-O2 affinity in humans more advantageous when O2 availability is limited? Humans with genetic mutations in hemoglobin structure resulting in high Hb-O2 affinity have shown attenuated cardiorespiratory adjustments during hypoxia both at rest and during exercise, providing unique insight into this central question. Therefore, the purpose of this review is to examine the influence of high Hb-O2 affinity during hypoxia through comparison of cardiovascular and respiratory adjustments elicited by humans with high Hb-O2 affinity compared to those with normal Hb-O2 affinity.

scholarly journals High altitude genetic adaptation in Tibetans: No role of increased hemoglobin–oxygen affinity

2014 ◽  
Vol 53 (1-2) ◽  
pp. 27-29 ◽  
Author(s):  
Tsewang Tashi ◽  
Tang Feng ◽  
Parvaiz Koul ◽  
Ricardo Amaru ◽  
Dottie Hussey ◽  
...  
Keyword(s):  
High Altitude ◽  
Oxygen Affinity ◽  
Genetic Adaptation ◽  
Hemoglobin Oxygen Affinity

scholarly journals Molecular Pathways Involved in the Development of Congenital Erythrocytosis

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1150
Author(s):  
Jana Tomc ◽  
Nataša Debeljak
Keyword(s):  
Signal Transduction ◽  
Iron Homeostasis ◽  
Molecular Mechanisms ◽  
Oxygen Affinity ◽  
Molecular Pathways ◽  
Disease Development ◽  
Post Translational Modifications ◽  
Hemoglobin Oxygen Affinity ◽  
Insight Into ◽  
Idiopathic Erythrocytosis

Patients with idiopathic erythrocytosis are directed to targeted genetic testing including nine genes involved in oxygen sensing pathway in kidneys, erythropoietin signal transduction in pre-erythrocytes and hemoglobin-oxygen affinity regulation in mature erythrocytes. However, in more than 60% of cases the genetic cause remains undiagnosed, suggesting that other genes and mechanisms must be involved in the disease development. This review aims to explore additional molecular mechanisms in recognized erythrocytosis pathways and propose new pathways associated with this rare hematological disorder. For this purpose, a comprehensive review of the literature was performed and different in silico tools were used. We identified genes involved in several mechanisms and molecular pathways, including mRNA transcriptional regulation, post-translational modifications, membrane transport, regulation of signal transduction, glucose metabolism and iron homeostasis, which have the potential to influence the main erythrocytosis-associated pathways. We provide valuable theoretical information for deeper insight into possible mechanisms of disease development. This information can be also helpful to improve the current diagnostic solutions for patients with idiopathic erythrocytosis.

scholarly journals CD73 and AMPD3 deficiency enhance metabolic performance via erythrocyte ATP that decreases hemoglobin oxygen affinity

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
William G. O’Brien III ◽  
Vladimir Berka ◽  
Ah-Lim Tsai ◽  
Zhaoyang Zhao ◽  
Cheng Chi Lee
Keyword(s):  
Oxygen Affinity ◽  
Hemoglobin Oxygen Affinity ◽  
Metabolic Performance
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