A broad diversity in oxygen affinity to haemoglobin

Area of Science:

• Physiology
• Biochemistry
• Clinical Medicine

Background:

• Haemoglobin-oxygen (Hb-O2) affinity, indicated by p50, is crucial for cellular oxygen delivery.
• Individual variations in p50 are often overlooked in clinical practice, despite potential implications for tissue hypoxia.
• Understanding p50 diversity is vital for optimizing oxygen availability in various physiological conditions.

Purpose of the Study:

• To investigate the diversity of Hb-O2 affinity (p50) in healthy volunteers.
• To assess the impact of maximal exercise on Hb-O2 affinity.
• To determine sex-based differences and the effect of endurance training on p50.

Main Methods:

• Measurement of oxyhaemoglobin dissociation curves (ODCs) in 60 volunteers (aged 18-40).
• ODCs were analyzed at rest and immediately after a VO2max test.
• Blood samples were analyzed for p50, 2,3-bisphosphoglycerate (2,3-BPG), and BPGM levels.

Main Results:

• Significant baseline p50 variation (over 7 mmHg) observed among participants.
• Maximal exercise induced a rightward shift in ODC, increasing p50 by up to 10 mmHg.
• Women exhibited lower baseline Hb-O2 affinity than men, linked to higher 2,3-BPG and BPGM.
• Endurance training did not affect baseline Hb-O2 affinity.

Conclusions:

• Baseline p50 diversity is substantial and requires clinical consideration for tissue oxygenation.
• Sex is a significant determinant of baseline Hb-O2 affinity.
• Venous blood samples are recommended for accurate p50 prediction via blood gas analysis.