Biochemical adaptation to chronic hypoxia of high altitude

The vital process of adaptation to a natural hypobaric environment has been studied in humans and small mammals living permanently in their native high-altitude environment. A group of humans and small mammals living at sea level, but otherwise similar to the high-altitude group, has also been studied and used as reference. The significance of both physiological and biochemical aspects of adaptation is evaluated here in terms of the teleologic principle that the main purpose of all metabolic and physiological processes in a living organism is the generation of enough energy to guarantee the formation, maintenance and procreation of cellular organization and structure, thus overcoming the natural entropic tendency toward disorganization. The results of our studies suggest that the physiological changes occurring during acute exposure to hypoxia, although extremely important in the regulation of uptake, conductance, and delivery of O₂ to its final place of utilization, do not represent the ultimate mechanisms in energy recovery. We present data strongly suggesting that a biochemical or molecular type of adaptation, most likely at the level of cytochrome c oxidase, is the ultimate mechanism for generating and controlling energy flow at high enough rates to maintain life under chronic hypoxic conditions.