The oxygen affinity of mammalian hemoglobins in the absence of 2,3-diphosphoglycerate in relation to body weight.

This study examines the oxygenation of mammalian hemoglobins from various species, relating it with their body weight. The research indicated that the previously reported negative correlation between an animal’s weight and the oxygen affinity of its blood is not observed when 2,3-diphosphoglycerate (DPG) is absent.

Introduction

• The objective of this research was to study the oxygen affinity of mammalian hemoglobins from different species in relation to body weight. Specifically, the researchers wanted to explore the presence or absence of a certain correlation (previously identified by Schmidt-Nielsen and Larimer in 1958) in the absence of 2,3-diphosphoglycerate (DPG).

Methodology

• The researchers studied different mammalian species including mouse, rabbit, Japanese monkey, human, sheep, llama, pig, cow, and horse.
• They examined the process of oxygenation of the hemoglobins in these species, in the absence of DPG, a key player in the regulation of oxygen binding and release in red blood cells.

Results & Discussion

• According to the results, the negative correlation between body weight and the oxygen affinity of the whole blood, as previously noted by Schmidt-Nielsen and Larimer, was not observed when DPG was not present.
• This suggests that DPG might play a crucial role in the correlation between body weight and oxygen affinity of mammalian hemoglobins. This correlation is part of a larger theory of adaptive evolution, which proposes that aspects of an animal’s physiology, such as oxygen transport efficiency via hemoglobin, may have evolved in relation to its body size.

Conclusion

• The study concludes that the correlation between an animal’s body weight and the oxygen affinity of its blood can only be fully appreciated when DPG is present. This implies that DPG plays an indispensable role in the oxygen-carrying capacity of hemoglobin, and therefore, in the supposed adaptive evolution of oxygen transport systems in different mammalian species.