Human whole-blood oxygen affinity: effect of temperature

Area of Science:

• Physiology
• Biophysics

Background:

• Hemoglobin's oxygen affinity is influenced by various factors, including temperature.
• Understanding these influences is crucial for comprehending oxygen transport in the human body.

Purpose of the Study:

• To investigate the effect of temperature changes on human whole-blood oxygen affinity.
• To determine the temperature independence of the oxygen dissociation curve's shape.
• To analyze the temperature dependency of the proton Haldane and Bohr factors.

Main Methods:

• Measurements of oxygen saturation (SO2) in human whole blood from six healthy donors.
• Experiments conducted across a wide SO2 range (1-99%) and temperatures (22, 27, 32, 37, 42°C).
• Simultaneous measurement of the total (proton) Haldane factor and assessment of proton liberation from hemoglobin.

Main Results:

• Temperature was found to have no influence on the shape of the oxygen dissociation curve.
• The temperature coefficient (delta log PO2/delta T) was independent of SO2.
• The proton Bohr factor demonstrated temperature dependency across the entire SO2 range.
• The exothermic oxygenation reaction released 42.7 kJ/mol of heat per monomeric hemoglobin.

Conclusions:

• The shape of the human oxyhemoglobin dissociation curve is unaffected by temperature.
• The proton Bohr factor's temperature dependency is consistent across all oxygen saturation levels.
• Hemoglobin oxygenation is an exothermic process with significant heat evolution.