Oxygen affinity and Bohr effect responses to 2,3-diphosphoglycerate in equine and human blood.

The research paper explores how the oxygen affinity and Bohr effect of blood rely on the levels of 2,3-diphosphoglycerate (DPG) in erythrocytes, comparing findings from trotter horses and healthy men. The research found both equine and human blood’s oxygen affinity to be similar in the absence of DPG, but with potentially significant differences as DPG levels increase.

Introduction to the Research Article

• The study set out to assess how blood oxygen affinity – the degree to which oxygen can attach itself to hemoglobin in blood cells – and the Bohr effect, which explains how carbon dioxide impacts oxygen’s ability to bind with hemoglobin, are influenced by the concentration of 2,3-diphosphoglycerate (DPG) in erythrocytes (red blood cells).
• The research was conducted on 24 trotter horses and 24 healthy men, and involved determining the oxygen tension at half saturation and standard conditions (P50st at pH 7.4, PCO2(40) mmHg and 37 degrees centigrade) and the carbon dioxide or fixed-acid-induced Bohr effect (dlogP50/dpH).

Findings in Absence of Measurable DPG

• When DPG was not detectable, the equine and human blood had comparable values of P50st (16.6 [0.6] and 16.2 [0.7] mmHg, respectively).

Findings as DPG Levels Increase

• As the levels of DPG rose, the P50st values in both equine and human blood also increased. However, the response in equine blood was significantly lower, at least up to physiological values, compared to human blood.
• For concentrations above 20 to 25 mumol gHb-1 of DPG, the difference in P50st values between the two species began to decrease because the response in human blood hit a plateau.

Interactions between Bohr Effect and DPG Concentration

• The relationship between the Bohr effect and DPG concentration showed that in both horses and men, the amount of DPG played a significant role in determining the relative size of carbon dioxide and fixed acid factors.
• The greatest difference between these two factors, which is linked to the oxylabile carbamino binding, was found in DPG-depleted blood. But while in men the difference disappeared with high DPG concentration, it remained measurable in horses.