For the individual permanently residing at sea level, hypoxia can be caused by external factors, such as a sudden arrival in Tibet, or by "internal impairments," within the body where cells receive insufficient oxygen. Regardless of the cause of the hypoxia, a wide range of disorders may occur.
How can Tibetans function normally at altitudes that would eventually capacity the rest of us? It is known that organisms may adjust who body functions, modify some metabolic pathways, and change the sensitivity of the "injury threshold" to increase a tolerance to hypoxia. But what is unclear is whether that adjustment is acclimatization, capable of occurring during an extended period in a high altitude environment, or adaptation, requiring several generations in high altitudes for tolerance to occur.
Tibet and its native population have previously offered researchers a "natural laboratory" for the study of hypoxia, the environment, and physiological responses to both. Past findings include verification that Tibetans are adaptive in nature, and have significantly less polycythemia (excessive red blood cells) and hypoventilation, normally found in "lowlanders'" mountain sickness. To compare genetic differences and resistant reactions between Tibetans and lowlanders could offer clues for preventing hypoxia, whether it is caused by a change in environment or as a result of the body's processes.
The authors of the study, "Intrinsic Characteristic Tolerance to Acute Hypoxia in Tibetans after Migrating to Low Altitude," are Zhao-Nian Zhou, J.G. Zhe
Contact: Donna Krupa
American Physiological Society