Regulation of Hemoglobin Function in Mammals

This survey of hemoglobin function in mammals reveals a broad range in oxygen affinity. The concentration of red cell 2,3-DPG varies widely among groups of mammals. Those animals (feloids and ruminants) that have very low levels of this intracellular mediator have hemoglobins of intrinsically low oxygen affinity which fail to respond to the addition of 2,3-DPG. Mammals which have adapted to various types of hypoxia tend to have increased oxygen affinity, primarily mediated through reduced levels of red cell 2,3 DPG. In contrast mammals who are experimentally subjected to low oxygen tensions develop decreased oxygen affinity owing to increased red cell 2,3-DPG. Mammals employ one of three different mechanisms for the maintenance of higher oxygen affinity of fetal red cells, compared to maternal red cells. Many of these phenomena can be satisfactorily explained at the molecular level but their adaptational significance is less clear.