Question

13. Which of the following would happen to the O₂ saturation curve of Hemoglobin in the presence of normal amounts of 2, 3 DPG if  a drug  were administered that prevents the binding of the 2,3 DPG to Hemoglobin:

1. The curve would be shifted to the right from that of normal red cells.
2. The concentration of O₂ necessary to saturate Hb would be higher than the normally required
3. O₂ binding at high P_O2 would be greatly decreased
4. The amount of O₂ delivered to the respiring tissue foe a given partial pressure of O2 (e.g. 40 mmHg at the capillaries) would be lower than normal.
5. No effect will take place on the affinity of Hemoglobin to O₂

Answer 1

Option D) The amount of oxygen delivered to the respuring tissue for a given partial pressure of oxygen would be lower than normal.

2,3 DPG has affinity towards deoxygenated haemoglobin and binds to it rather than oxygenated haemoglobin. When it binds to deoxygenated haemoglobin, it also forces some bound oxygen to be released. This allows oxygen to be released in tissues that require it. So, an increase in concentration of 2,3-DPG increases amount of oxygen delivered to the tissues while a decrease in its concentration as in this case ( a drug which prevents its binding to haemoglobin) would decrese the amount of oxygen delivered to tissues.