Enzymatic Mechanisms of Red Cell Adaptation to Anemia
It has long been known that many anemic patients adjust to their low hemoglobin levels and tend to have clinical symptoms less severe than might be expected. It is now generally accepted that the increased level of DPG in red blood cells of anemic patients plays a major role in this adjustment through its right- shifting effect on the erythrocyte-oxygen affinity curve. The biochemical mechanisms by which DPG levels are increased in anemia have yet to be satisfactorily demonstrated. It is known that DPG is produced by a two enzyme shunt in the glycolytic pathway (Rapoport and Luebering, 1950). The DPG shunt bypasses an ATP producing enzyme, phosphoglycerate kinase. There are three possible mechanisms by which DPG levels may be elevated: The first, a block in the lower part of the pathway, is trivial in our considerations here because it leads to decreased glycolysis and to hemolytic anemia if the block is severe enough. The second mechanism for elevating DPG levels would be an increase in the DPG shunt activity relative to the phosphoglycerate kinase step. It seems unlikely that this is the predominant mechanism because this implies that there should be a tendency for ATP levels to be low in anemia and this is not the case in most types of anemia.
KeywordsAplastic Anemia Anemic Patient Enzymatic Mechanism Cell Water Phosphofructokinase Activation
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