Lower levels of 2,3-DPG in red cells result in what effect on hemoglobin's affinity for oxygen?

Lower levels of 2,3-DPG in red blood cells lead to an increased affinity of hemoglobin for oxygen. This occurs because 2,3-DPG (2,3-diphosphoglycerate) normally binds to hemoglobin, causing a conformational change that decreases its affinity for oxygen, promoting the release of oxygen to the tissues. When the concentration of 2,3-DPG is low, hemoglobin retains its oxygen more tightly and does not release it as readily to the tissues.

This mechanism is crucial for the regulation of oxygen delivery; lower levels of 2,3-DPG can be seen in certain conditions, such as with the use of stored red blood cells, which can result in less effective oxygen transport to tissues. Thus, when 2,3-DPG levels decrease, hemoglobin's affinity for oxygen increases, meaning that less oxygen is released to the tissues. This highlights the important role of 2,3-DPG in the overall physiology of oxygen delivery and utilization in the body.