Abstract
This investigation was undertaken to study the role of changes in the level of erythrocytic 2, 3-DPG during adaptation and acclimatization reactions of organisms in a hypoxic environment. The following are the results obtained from human subjects and animals when they were exposed to hypoxic environments in a hypobaric chamber or by the inhalation of hypoxic gas.
1) The relationship among the 2, 3-DPG levels of normal subject's blood, anemic patient's blood as well as ACD-stored blood and blood P50 value was found to be as follows: the P50 is increased by the presence of 2, 3-DPG and the right shift of the oxyhemoglobin-dissociation curve was reconfirmed.
2) Differences in human subjects and species of animals were observed in 2, 3-DPG concentration at sea-level. There was a negative correlation between the hemoglobin concentration and the 2, 3-DPG concentration. Hence, it is presumed that the tolerance for hypoxic environment among different species is related to the 2, 3-DPG level.
3) In experiments where human subjects were exposed to acute hypoxic environment in a hypobaric chamber, the 2, 3-DPG level increased rapidly after exposure. In experiments where human subjects and animals (dogs, rabbits) were exposed to chronic hypoxic environment for 7-14 days, a high level of 2, 3-DPG was maintained during the period of exposure. It decreased rapidly when the exposure was terminated.
The 2, 3-DPG is considered to be one of the important mechanisms of adaptation and acclimatization that facilitates the supply of oxygen to hypoxic tissue resulting from a hypoxic environment. This mechanism can be added to the generally recognized compensatory mechanisms, such as increased cardiopulmonary function, or increased hematopoietic activity, etc.
4) Rabbits were exposed to various oxygen concentrations of hypoxic gas. The 2, 3-DPG level showed a steady increase with 10% oxygen; however, it was unstable at below 10%. This report suggests that there is a limit in the adaptability of increased 2, 3-DPG levels to hypoxia and that the effects is unreliable in a altitude environment above 5, 500 meters (below 1/2 Ata).
