- There is an important adaptation that occurs with red blood cells in higher altitudes. 
- At sea level altitudes the arterial vs venous pO2 or the oxygen pressure is significantly different and hemoglobin releases 38% of its bound oxygen.
- There is an increase in BPG at higher altitudes which causes the curve to shift to the right because there is a lower affinity for oxygen.
- However in the higher altitudes starting around 4500m, hemoglobin can only drop off 30% of its oxygen. 
- Thus, in higher-altitudes the amount of oxygen that binds to the hemoglobin is less but the amount of oxygen released is more. 

Grand Valley State University

- There are additional compounds in the blood stream that effect the oxygen levels besides CO2
- The compound 2,3-bisphosphoglycerate (BPG) binds to deoxyhemoglobin (empty O2 bound hemoglobin) 
- BPG in blood decreases the oxygen affinity by keeping hemoglobin in the deoxyhemoglobin conformation. 
- In the absence of BPG, O2 would not release from the hemoglobin.

2,3-bisphosphoglycerate (BPG)

Voet, D., Voet, J. G., & Pratt, C. W. (2013). Chapter 7: Protein Function: Myoglobin and Hemoglobin, Muscle Contractions, and Antibodies. In Fundamentals of biochemistry: Life at the molecular level (4th ed., pp. 176-216). Hoboken, NJ: Wiley. Retrieved February 21, 2021, from archive.org.

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